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Biomedical subjects

D Anderson

Publications and source records attributed to D Anderson.

At least 145 records · Page 8Linked to original sources
PubMed1999

Stealth virus epidemic in the Mohave Valley: severe vacuolating encephalopathy in a child presenting with a behavioral disorder.

An infectious illness, attributed to atypically structured cytopathic "stealth" viruses, occurred in 1996 in the Mohave Valley region of the United States. A stealth virus-infected child from this region has developed a severe noninflammatory, vacuolating (spongiform) en cephalopathy. The illness initially presented as a behavioral problem without overt neurological signs. Extensive investigations, including repeated magnetic resonance imaging, two brain biopsies, and stealth virus cultures, have helped define the disease process occurring in this child. Significant clinical benefit with apparent retardation of disease progression occurred during a 6-week course of ganciclovir therapy. The potential contributing role of stealth virus infections in children presenting with behavioral problems needs to be addressed.

Antiviral Agents↗
PubMed1999

In vivo real-time analysis of intraperitoneal radiolabeled tumor cell movement during laparoscopy.

PURPOSE: A porcine model has been developed to allow the real-time imaging of radiolabeled tumor cell movement throughout the peritoneal cavity, both at rest and during carbon dioxide insufflation. METHODS: Fifteen 30-kg domestic white female pigs were used. Under anesthesia, 15 to 20 million radiolabeled human colorectal tumor cells (LIM1215) were introduced into the peritoneal cavity under laparoscopic vision into the pelvis. Radiolabeled tumor cell movement was examined by using a 25-cm-diameter, low-energy mobile gamma camera with high resolution collimator. Tumor cell movement and distribution during two hours without insufflation was examined in four pigs. Then tumor cell movement and distribution during two hours with CO2 insufflation was examined in four pigs. In a further four pigs, tumor cells were then mixed with blood and injected into the peritoneal cavity and the effect of no insufflation vs. insufflation was noted. A further three pigs were examined with manipulation of the intra-abdominal contents after injection of LIM1215 cells into the peritoneal cavity. Venting insufflating CO2 was filtered for tumor cells. RESULTS: Widespread intraperitoneal distribution of tumor cells from the pelvis was identified both with CO2 insufflation of the peritoneal cavity and without insufflation. Tumor cells dispersed throughout the peritoneal cavity at a slower rate without carbon dioxide insufflation. There was a differential rate of tumor cell movement to the left upper quadrant and right upper quadrant with insufflation and without insufflation. Blood within the peritoneal cavity and an extended contact of the laparoscopic trocars with the peritoneal cavity in this setting increased contamination of the trocars and trocar sites with tumor cells. Tumor cells were identified on laparoscopic instruments in all experiments. No evidence of aerosolization of tumor cells was found. CONCLUSION: Tumor cells move throughout the peritoneal cavity both at rest and during CO2 insufflation. The pattern of tumor cell dispersion differs with CO2 insufflation. The presence of blood and extended contact of trocars with peritoneal contents are a major factor in trocar and trocar site tumor cell contamination.

Animals↗
PubMed1999

Stimulant medication for the child with attention-deficit/hyperactivity disorder.

Stimulant medications have been used to manage the associated symptoms of ADHD including inattention, developmentally inappropriate levels of activity, distractibility, and impulsivity. To date, clinical trials clearly have established the efficacy of the stimulants on the core symptoms of ADHD and associated aggression. Although the stimulants improve classroom productivity and behavior, few data have demonstrated the effectiveness of the stimulants on academic achievement. Finally, there has been a paucity of data on the long-term efficacy and safety of stimulants. Recommendations are made for future research studies that examine the integration of stimulant medication with other psychosocial therapies, particularly behavior management.

Aggression↗
PubMed1999

Fatal Chaetomium cerebritis in a bone marrow transplant patient.

The number of opportunistic infections in the central nervous system (CNS) has been steadily increasing because of a rising number of immunocompromised patients. A rare form of CNS infection can be caused by Chaetomium species, one of the largest genera of saprophytic ascomycetes. The CNS lesions in the present case were caused by Chaetomium atrobrunneum. The main characteristic of almost all Chaetomium species is presence of hairs or setae covering the ascomata. Microbiological studies are the only definitive way to correctly identify this fungal organism. The rapid evolvement of the cerebral infection suggests that the brain tissue provides a favorable environment for growth and proliferation of these fungi. This is the second documented case of a fatal brain abscess caused by Chaetomium atrobrunneum, and the first case report in a bone marrow transplant patient.

Adult↗
PubMed1999

Optimal clip application and intraoperative angiography for intracranial aneurysms.

BACKGROUND: The actual incidence of residual aneurysm after clipping is unknown. The natural history of residual aneurysm can be regrowth and hemorrhage. Intraoperative angiography offers a cost-effective, safe interdiction to the problem of residual aneurysm and parent vessel stenosis. METHODS/RESULTS: Forty consecutive patients harboring 54 aneurysms underwent 42 operative procedures to clip 52 aneurysms, during which 220 intraoperative angiographic runs were performed. Ninety-three percent of the procedures were performed on patients with acute subarachnoid hemorrhage. There were 4 giant (>2.5 cm, 4/52 = 8%, all anterior circulation), 21 large (1.0-2.5 cm, 21/52 = 40%, 16/ 21 = 76% anterior circulation, 6/21 = 28% posterior circulation), and 27 small (<1.0 cm, 27/52-52%, 22/27 = 81% anterior circulation, 5/27 = 18% posterior circulation) aneurysms. Intraoperative angiography led to clip adjustment in 18/52 = 34% of aneurysms (4/18 = 22% for parent artery stenosis, 8/18 = 44% for residual aneurysm and 6/18 = 33% for both). Of the 18 adjustments made, 16 = 88% were made on giant or large aneurysms and two were small (one was a complex anterior communicating and one was a vertebral junction aneurysm). Follow-up angiography was performed on 26/42 = 62% of operative cases. Postoperative angiography confirmed intraoperative angiography in all cases. Two complications occurred during 220 angiographic runs: one embolic stroke and one incident of equipment failure. CONCLUSION: A grading scale was applied to test the relationship between anatomical site and size as they relate to the necessity for clip adjustment for complete aneurysm obliteration and/or parent artery compromise. Significance was related to site (basilar bifurcation, anterior communicating, middle cerebral bifurcation, and ophthalmic) and size (>1.0 cm), both as independent and codependent variables. An analysis of the cost-effectiveness of intraoperative angiography was demonstrated.

Adult↗
PubMed1999

Evaluation of a self-paced education package on violence against women for rural community-based health workers.

There are no reported education programs specifically focusing on the needs of rural health workers in the area of violence against women. The most commonly reported contact sought by women experiencing injuries and health problems associated with violence and abuse is with health workers. Women report a failure by health workers to make direct enquires, which may be due to their lack of education and confidence in responding to these issues. A convenience sample of 60 community-based rural health workers from a range of occupations and settings within the Wide Bay Health Region, Queensland, participated in the evaluation of a self-paced, distance education package on violence against women. The package contained seven modules. These included written and audio tape material, and activities that together formed a community development approach to addressing the needs in the participants' local community. Participants were given a mentor and teleconference support during the 8 weeks allocated to complete the package. A pre- and post-course evaluation, containing quantitative and qualitative data, was completed. Analysis of the quantitative data identified significant changes in participants' knowledge, and the qualitative data highlighted an increased sense of confidence in assisting women, forming support networks and using resources more effectively. Participants reported the most useful aspects of the package were: (i) modular- and user-friendly format; (ii) flexible, practical, health-focused content; and (iii) real world examples.

Adult↗
PubMed1999

Statistical analysis of adaptive response in sister chromatid exchanges in human lymphocytes after treatment with very low and extremely low doses of N-methyl-N'-nitro-N-nitrosoguanidine using a study design to control variability.

Previous studies have been interpreted as suggesting that low concentrations of N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) have an adaptive effect in the cultured lymphocytes of responsive donors (that is, the cells are protected against the mutagenic effects of a subsequent challenge with a higher concentration of MNNG). The objectives of the present study were to investigate, under stringent experimental conditions, whether a protective effect exists at very low and extremely low doses of MNNG (10(-8) and 10(-24) M, respectively). Peripheral blood lymphocytes from a donor considered responsive in a previous study were stimulated to divide and were cultured under standard conditions. Pre-adaptive treatments with dilutions of MNNG were added to the cultures repeatedly before a challenge treatment with MNNG. Bromodeoxyuridine was added at the same time as the challenge treatment and, following mitotic arrest, cells were differentially stained so that the number of sister chromatid exchanges (SCEs) could be counted. The study was designed to address potential criticisms of earlier studies which did not include replicate cultures. Samples of blood were divided into two identical batches for independent processing. Five replicate cultures were prepared for each combination of pre-adaptive and challenge treatments in each batch. The complete experiment was repeated to provide a further test of the consistency of results. Five replicates per treatment combination were chosen in an attempt to provide an experiment of adequate statistical power. Considerable precautions were taken to minimise the effect of factors outside experimental control on the results. Scoring was done by three scorers. In order to minimise inter-scorer variation, 240 cells were scored at each treatment observation (five cells per-scorer, three scorers per culture, four cultures per batch, two batches per experiment and two experiments). The study was designed in this way to take account of the sources of variability to ensure that any response obtained would exceed that obtainable by experimental variability alone. A high level of quality assurance monitoring was undertaken throughout the investigation. Two measures of SCE induction were used: (i) the mean frequency of SCEs; (iii) proportion of cells with at least 20 SCEs. In both experiments, the challenge concentration of MNNG significantly increased SCE frequency. There were, however, highly significant differences between the two experiments. The proportion of high frequency cells (HFCs) in Experiment 1 was increased significantly; the proportion of HFCs was also increased in Experiment 2, but the increase was not statistically significant. The pre-adaptive concentrations of MNNG included an extremely low dilution of 6.8 x 10(-24) M and a very low dilution of 6.8 x 10(-8) M in Experiment 1 and 1.4 x 10(-7) M in Experiment 2. The various pre-adaptive concentrations used had no consistent protective effect against the SCE-inducing capacity of the challenge concentration of MNNG of 6.8 x 10(-6) M. It is concluded that an adaptive response to the alkylating agent MNNG could not be demonstrated in cultured human lymphocytes. Neither a very low nor an extremely low dilution of MNNG elicited an adaptive response in terms of SCE induction (measured either as SCE frequency or as proportion of HFCs). This is in contradiction to previous reports published by us and other groups. This study was carefully designed with large numbers of replicates, a preliminary statistical power calculation, predefined comparisons and extensive quality assurance at each treatment administration. Despite these precautions the variability between scorers and between batches was much larger than anticipated. This resulted in some statistically significant differences, but these are likely to be false positives. Our findings indicate the need for such methodological refinement in human cell adaptive response studies.

Carcinogens↗
PubMed1999

Forecasting hospital expenditure in Victoria: lessons from Europe and Canada.

This paper specifies an econometric model to forecast State government expenditure on recognised public hospitals in Victoria. The OECD's recent cross-country econometric work exploring factors affecting health spending was instructive. The model found that Victorian Gross State Product, population aged under 4 years, the mix of public and private patients in public hospitals, introduction of casemix funding and funding cuts, the proportion of public beds to total beds in Victoria and technology significantly impacted on expenditure. The model may have application internationally for forecasting health costs, particularly in short and medium-term budgetary cycles.

Adolescent↗
PubMed1999

Human monoclonal antibodies isolated from spontaneous Epstein-Barr virus-transformed tumors of Hu-SPL-SCID mice and specific for fusion protein display broad neutralizing activity toward respiratory syncytial virus.

Two human monoclonal antibodies, RF-1 and RF-2, specifically recognize the fusion protein of the human respiratory syncytial virus (RSV). These were isolated from spontaneous tumors in SCID mice reconstituted with human splenocytes and boosted with fusion protein. The tumors consisted of Epstein-Barr virus-transformed human B cells in animals with antigen-specific antibody titers>105. The binding affinity of RF-1 and RF-2 to the fusion protein is 1010 and 109 M-1, respectively. The antibodies bind specifically to a conformational epitope of the fusion protein on RSV-infected HEp-2 cells. Both antibodies display virus-neutralizing properties in vitro at concentrations varying between 8 and 1000 ng/mL. Virus neutralization applies to a broad variety of wild and laboratory-adapted virus strains belonging to both virus types A and B. These antibodies are potential candidates for passive immunotherapy of severe RSV infections.

Animals↗
PubMed1999

Quantification of insensible water loss associated with insufflation of nonhumidified CO2 in patients undergoing laparoscopic surgery.

A growing number of surgical procedures of increased duration are being performed using laparoscopic techniques. No study to date has quantitated the potential insensible water loss associated with laparoscopic surgical procedures as a result of intra-abdominal humidification of insufflated nonhumidified CO2 gas. The purpose of this study was to quantitate this insensible water loss by measuring the CO2 gas volume consumed and the relative humidity of the vented gas. Ten patients presenting for elective procedures were enrolled in this descriptive prospective IRB-approved study. After secondary trocar placement and attainment of the desired intra-abdominal pressure, vented laparoscopic gas was passed directly through a dewpoint monitor sensor. Determinations of dewpoint and gas temperature were made immediately after the start of the surgical procedure and every 15 minutes thereafter until completion. Dew-point temperature was converted to relative humidity, which was used to determine the water vapor content of the gas. The actual water content (absolute humidity) of the vented laparoscopic gas was then calculated from the water vapor volume. The mean relative humidity of the vented laparoscopic gas was 92.2% +/- 0.8%. The mean laparoscopic gas flow rate was 42.0 +/- 5.0 L/h. The mean volume of water (absolute humidity) loss attributed to humidification of dry CO2 was found to be less than 1 mL/h. Insufflation of dry CO2 during laparoscopic procedures therefore results in insignificant insensible water loss.

Adult↗
PubMed1999

Pacemaker-induced superior vena cava obstruction: bypass using the intact azygous vein.

Superior vena cava thrombosis due to pacemaker leads is an uncommon but well-recognized complication. Its pathogenesis remains unclear and it is usually a benign condition. Superior vena cava occlusion can be successfully treated by thrombolysis and anticoagulation if the occlusion is recent, balloon venoplasty and stenting, and surgery. We describe a case of superior vena cava obstruction successfully bypassed using the intact native azygous vein, a technique that has not been described before, with excellent long-term results.

Humans↗
PubMed1999

Intimate justice. II: Fostering mutuality, reciprocity, and accommodation in therapy for psychological abuse.

This article presents part of the findings of a study of psychological abuse and physical violence in couples who voluntarily entered therapy. The study found that most of the men exhibited patterns of deception, devaluation, and dictatorial attitudes with their women partners and that these patterns were a considerable barrier to mutuality, reciprocity, and accommodation in the partnership. The researchers developed four interventions to challenge the men to change these patterns: true intentions, no free rides, the perception paradox, and the infallibility fallacy. The study was based on intimate justice theory, a developing clinical approach to therapy based on ethical theory.

Adult↗
PubMed1999

Motor performance with a simulated artificial limb.

The present study was conducted to examine performance differences on a reaching and grasping task related to an activity of daily living. This involved either the anatomical limb or a simulated artificial limb. College-aged volunteers (2 men and 4 women), one of whom was left-handed, performed the reaching and grasping task. The apparatus, placed on a table before the seated participant, was a square wooden board which contained a starting key and holes for the insertion and removal of a small Fiberglas dowel. At the beginning of the trial the participant depressed the start key, reached forward and grasped the dowel, and then returned the dowel to a finishing hole located directly in front of the start key. The results of 2 (side) x 2 (type of limb) repeated-measures multivariate analyses of variance on the mean and standard deviation of the movement times showed a significant main effect for type of limb (Wilks lambda 3,3 = .047 and .079, respectively, p < .05). Analyses of variance on mean total transport time, extension time, flexion time, and their standard deviations showed that times were slower and less consistent with the prosthesis for all measures. These results and those of later research should be focused on the development of training principles for both therapists and individuals with an amputation. In addition, the simulated prosthesis is an excellent experimental model for basic and clinical research in the control and acquisition of coordinated movement.

Activities of Daily Living↗
PubMed1999

An investigation of male-mediated F1 effects in mice treated acutely and sub-chronically with urethane.

In order to investigate the alleged potential of paternally administered urethane to cause foetal abnormalities and heritable tumours, male CD-1 mice were treated with urethane, either acutely by intraperitoneal injection at doses of 1.25 and 1.75 g/kg bodyweight (bwt) or sub-chronically in the drinking water at 1.25 for 10 weeks, and 3.75 mg/ml for 9 weeks or vehicle for the control groups. They were mated to untreated females 1 week later. Uterine contents of half the pregnant females were examined just before full term, while the remaining females were allowed to deliver their litters. The resulting F1 offspring were observed for approximately 18 months and 12 months for acute and sub-chronic exposures respectively and subjected to necropsy examination. Some of the mice treated acutely with 1.75 g/kg bwt exhibited partial infertility but none of those treated with 1.25 g/kg bwt had an adverse effect on their reproductive ability. There was no genetic effect of acute urethane treatment on male germ cells as indicated by dominant lethality. After birth, there was an increase (P < 0.05) in post-implantation deaths possibly due to perinatal mortality. There was an increased incidence and earlier onset of liver tumours induced in F1 male offspring from F0 males treated with 1.75 g/kg bwt, (20.7% vs. 10.1%, P = 0.026) but not in the female offspring. F1 males from both treatment groups had mean bodyweights significantly higher than controls (P < 0.01). Some males from each dose group of the acute study were examined using the restriction site mutation assay involving analysis of exon sequences. No mutations were identified in testes, liver or spleen of DNA isolated from the urethane-treated animals. No reproductive or genetic effects were seen with sub-chronic treatment at either 1.25 or 3.75 mg/ml urethane nor was there any predisposition of F1 animals to tumours although observation times were shorter.

Abnormalities, Drug-Induced↗
PubMed1999

Aflatoxin exposure and DNA damage in the comet assay in individuals from the Gambia, West Africa.

The single cell gel electrophoresis assay (Comet assay) was used to measure DNA damage in peripheral lymphocytes from a group of individuals from The Gambia in order to determine whether such damage could be associated with increased exposure to aflatoxin in this population. Responses obtained were correlated to responses previously obtained [1] in a cross-sectional study in the same individuals of various cytogenetic alterations [chromosomal aberrations, micronuclei (crest positive and negative staining), and sister chromatid exchanges], and aflatoxin-albumin adducts. Analysis of variance methods were used to assess the effects of smoking, GSTM1 genotype, sex, age, and smoking status. A comparison was also made between The Gambian individuals and a group of healthy, non-smoking volunteers in the United Kingdom where aflatoxin exposure would be expected to be low. From the earlier study [1], it was determined that the levels of the sister chromatid exchanges and micronuclei were higher in The Gambian group than in a European group where aflatoxin exposure was lower, but that there were no correlations between the adduct levels and the cytogenetic abnormalities at the individual level. In the present study, DNA damage as measured in the Comet assay was not significantly higher than in the healthy United Kingdom volunteers. In addition, there were no associations between cytogenetic damage, GSTM1 genotype, age, sex, lifestyle factors (smoking and aflatoxin exposure), and Comet response at the individual level. Comet response was higher in females than males in The Gambia if one outlier was excluded from analysis and not taking into account other sources of variability. It would appear that DNA damage as measured in the Comet assay in peripheral blood lymphocytes is not a sensitive genotoxic marker of aflatoxin exposure in this population.

Adolescent↗