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Biomedical subjects

D Carlson

Publications and source records attributed to D Carlson.

At least 19 recordsLinked to original sources
PubMed2007

Assessment of zinc and copper status in weaned piglets in relation to dietary zinc and copper supply.

The aim of the study was to determine the effect of weaning and the effect of increasing dietary zinc concentrations on the zinc and copper status of weaned piglets (study 1) and to study the effect of high concentrations of dietary zinc and/or copper on zinc and copper status of weaned piglets (study 2). Study 1 included 54 piglets (six litters of nine piglets). One piglet from every litter was killed 1 day before weaning. The remaining 48 piglets were allocated at weaning (28 days) to four dietary zinc treatments (100, 250, 1000 or 2500 ppm) and subsequently killed 1-2, 5-6 or 14-15 days after weaning. Study 2 included 48 piglets (six litters of eight piglets) allocated to four dietary treatments, consisting of low or high dietary zinc (100 or 2500 ppm) in combination with low or high dietary copper (20 or 175 ppm). All piglets in study 2 were killed 5-7 days after weaning. In both studies, the trace mineral status was assessed by zinc and copper concentrations and alkaline phosphatase (AP) activity in plasma and mucosal tissue. In study 2, lymphocyte metallothionein (MT) mRNA and intestinal mucosa MT mRNA concentrations were included as zinc status markers. The results showed that the zinc status, measured as zinc in plasma and mucosa, was not affected by weaning of the piglets. Plasma copper concentrations decreased during the first 2 weeks after weaning. High dietary copper concentrations did not affect the concentration of copper in plasma, but increased the concentration of copper in mucosa and the concentration of zinc in plasma. The dietary zinc treatments increased the zinc concentration in plasma as well as the zinc and MT mRNA concentration in mucosa. Lymphocyte MT mRNA concentrations did not reflect the differences in dietary zinc supplementation.

Administration, Oral↗
PubMed2005

Gliosarcoma cell death after radiosurgery in a rat model.

Therapeutic radiation and subsequent detection of tumor cell death has been performed mainly in vitro systems, making it difficult to accurately characterize the mechanisms of tumor cell death after radiosurgery. To better characterize what occurs to glioma cells after radiation therapy, we developed a rat model using the 9L gliosarcoma cell line implanted reproducibly to the caudate nucleus in rats. After 1 Gy radiation, 9L tumors in vivo induced mainly necrosis (determined by trypan blue exclusion) of 10 - 74 % at 6 - 72 hours post-radiation. This is in contrast to a previous in vitro study which demonstrated that 18 Gy of radiation induces considerably less cell death as determined by trypan blue exclusion (approximately 20 - 25 % at 6 - 72 hours post-radiation). However, significant amounts of apoptosis were detected as early as 6 hours after radiation. Apoptosis determination was by annexin V (marker of early apoptosis) and propidium iodide (marker of membrane stability) staining followed by flow cytometry detection. When caspase 3 and caspase 8 enzymatic activities (mediators of apoptosis) were measured from freshly explanted tumor cells, peak activity was found 6 hours after 1 Gy radiation (p < 0.01). Taken together, these data indicate the presence of apoptosis early after radiation therapy (1 Gy) which progressed to necrosis in a unique in vivo model of gliosarcoma that may prove useful in determining new therapeutic approaches to radiation therapy and tumor cell biology.

Animals↗
PubMed2004

Additional dietary zinc for weaning piglets is associated with elevated concentrations of serum IGF-I.

Two experiments were performed in order to study how weaning and post-weaning dietary zinc level affect serum IGF-I. Further, whether the growth-enhancing effect of 2500 ppm of dietary zinc (Zn2500) and/or 175 ppm of dietary copper (Cu175) in post-weaning diets is associated with elevated serum IGF-I levels in piglets was studied. Experiment 1 included 54 piglets (six litters of nine piglets). One piglet from every litter was assigned to a control group (blood sampled 1 day before weaning). At weaning the remaining eight piglets from every litter were allocated randomly to four dietary treatments with increasing zinc inclusions (Zn100, Zn250, Zn1000, Zn2500). In exp. 2, 48 piglets (six litters of eight piglets) were allocated to four dietary treatments (Zn100, Zn100Cu175, Zn2500, Zn2500Cu175). All piglets in exp. 1 were blood sampled at -1, 1-2, 5-6 or 14-15 days after weaning and in exp. 2 blood samples were taken from all pigs 5-7 days after weaning. Feed intake was recorded per pen (two piglets) and weight gain was recorded for every piglet. Just after weaning feed intake was very low, piglets lost weight and serum IGF-I decreased in exp. 1. However, the piglets fed 2500 ppm of zinc reached pre-weaning levels of serum IGF-I at 14-15 days post-weaning, whereas piglets receiving lower zinc levels showed no changes in serum IGF-I. In exp. 2, additional dietary zinc in weaning diets for piglets was found to be associated with increased feed intake, improved growth rate and increased serum IGF-I. High levels of dietary copper did not affect any of these measurements. Zinc-induced rise in serum IGF-I was partly due to increased feed intake. After correcting for differences in feed intake, zinc significantly increased serum IGF-I. However, to completely separate effects of feed intake from effects of zinc status, pair-feeding should be considered in future studies.

Administration, Oral↗
PubMed2001

Students with disabilities: a national survey of participation in school activities.

INTRODUCTION: The policies of integration and full inclusion in school activities have been enacted to promote the independence and social participation of students with disabilities. This study examined the nature and extent of participation in schools by students with disabilities in the context of the physical, social and psychological features of the school environment. METHOD: A national survey was completed by 1180 teachers of students with disabilities in the US describing student participation in school activities encompassing involvement in social activities, sports, academic and artistic/creative endeavours. RESULTS/CONCLUSIONS: Multivariate analysis revealed that school life in elementary, middle and high school could be defined by six distinct factors describing individual and group roles. Structural equation modelling yielded a second order latent variable that captured the complex and multi-dimensional aspect of participation, accounting for availability, eligibility, student characteristics/status, and student choice within a larger framework of participation.

Adolescent↗
PubMed2001

Intensity modulation using multileaf collimators: current status.

Intensity-modulated radiation therapy (IMRT) extends the capability of 3D conformal methods (3D-CRT). Studies show that these methods can clinically reduce complications and can allow a larger safety margin for dose escalation. The ultimate goal is improved survival and improved quality of life. IMRT methods typically require more fields, or segments, and more monitor units for a given dose, as compared to conventional CRT methods. Because of this, some multileaf collimator (MLC) parameters take on more importance. A review of current standard MLC configurations are discussed, along with the concept of integral dose. An effective quality assurance (QA) program for IMRT involves more than dose modeling of the MLC. Integrity of data flowing from 3D radiograph databases to treatment planning to delivery sequencing files to verify-and-record function is required. End users need to be aware of differences in commercial availability vs. in-house developments for configuring a system. Great strides have been made in streamlining the whole process. This is evidenced by the first major symposium on community-based IMRT. Research continues to improve accuracy and productivity.

Humans↗
PubMed2001

IMRT: high-definition radiation therapy in a community hospital.

A multileaf collimator (MLC)-based intensity-modulated radiation therapy (IMRT) program was implemented successfully at Monmouth Medical Center, a community hospital at Long Branch, New Jersey. Our clinical experience gained in the treatment of over 80 patients using IMRT for prostate, head and neck, and brain is reviewed, and some of the clinical issues are also, discussed. Implementation of the IMRT requires a treatment planning system, computer-controlled beam-shaping aperture, electronic record and verify system, and a good physics quality assurance program. These components, by grouping them efficiently, have created a seamless workflow for our complete radiotherapy process of IMRT. Each of these radiotherapy processes are discussed for clarity and the clinical importance is also evaluated. Of particular interest is inverse treatment planning that will impact treatment delivery such as beam orientation, treatment ports, and organ motion of IMRT. A checklist for physics and departmental quality assurance is suggested, with the intention of providing systematic workflow, making IMRT feasible at a community medical center setting. This is especially important because most of our cancer patients received radiation therapy locally. Lastly, the reimbursement issue affecting the implementation of IMRT at our medical center is also discussed to justify this new treatment protocol for future clinical outcomes.

Head and Neck Neoplasms↗
PubMed2001

The WHO quality of life assessment instrument (WHOQOL-Bref): the importance of its items for cross-cultural research.

One of the fundamental issues in the area of assessment of quality of life is to determine what is important to the individuals' quality of life. This is even more crucial when the instrument is for use in diverse cultural settings. This paper reports on the importance ratings on WHOQOL-Bref items obtained as a part of WHOQOL pilot field trial on 4804 respondents from 15 centres from 14 developed and developing countries using 12 languages. All items were rated as moderately or more important, but this was expected because the items were selected by extensive qualitative research for their salience across the centres. Significant differences on mean importance ratings were found between centres, but rank orders of item for their importance showed highly significant correlations between centres. This was especially true for items in the top and the bottom thirds of the item list arranged by overall importance. Most items were rated as more important by women compared to men and by younger compared to older persons. The results are discussed for their relevance in cross-cultural research on quality of life assessment.

Adolescent↗
PubMed2001

The affective and memorial components of distinctiveness-based illusory correlations.

Two studies were conducted to test a model of the distinctiveness-based illusory correlation (IC) phenomenon that suggests there are two components operating with ICs: cognitive memorial, and affective. In Expt 1 (N = 118), two stimulus arrays were developed that were equivalent in regards to valence (good or bad extremity) but differed in regards to the affect dimension (high or low emotional intensity). Consistent with predictions drawn from the proposed model, the magnitude of the IC effect was higher in the high emotional intensity than in the low emotional intensity condition, but only significantly so on the measures (estimation and general evaluation) that have been hypothesized to be most sensitive to the affective component. In Expt 2 (N = 52), the affective qualities were matched and the valence properties varied in two stimulus arrays. As predicted, the IC effect differed significantly between conditions only on the measure (assignment) thought to be most sensitive to the memorial component. The results are discussed in terms of the implications of the findings for the proposed mechanisms of illusory correlation.

Adult↗
PubMed2001

Parental preferences in the management of vesicoureteral reflux.

PURPOSE: We determined parental preferences for the treatment of vesicoureteral reflux in their child. MATERIALS AND METHODS: Parents of children with vesicoureteral reflux were prospectively recruited to evaluate choices in reflux management. In each case a standard questionnaire that described the treatment options for reflux was administered. Parents were asked to choose between long-term antibacterial prophylaxis with annual radiography studies and open or endoscopic treatment at each of 1 to 5 years of followup. They were also given the choice between open or endoscopic treatment. Annual resolution and/or correction rates provided for medical, surgical and endoscopic management were 20%, 95% to 100% and 80% after 1 or 2 injections, respectively. RESULTS: We queried 91 families of female (81%) and male (19%) patients. Average duration of reflux followup was 2 years and mean patient age was 49.8 months. At diagnosis reflux was grades I to II in 65% of cases, grade III in 26% and grades IV to V in 9%. The majority of parents chose daily antibiotics over surgery if the child was predicted to have vesicoureteral reflux for 1 to 4 years. However, the majority chose ureteral reimplantation over daily antibiotics and yearly x-ray if a 5-year course was predicted. In contrast, parents chose daily antibiotics rather than endoscopic treatment if the anticipated interval was 1 to 3 years. After 3 years the majority preferred the endoscopic approach. Also, 60% of parents stated that they would choose endoscopic treatment over reimplantation, although the child may require repeat endoscopic treatment and there was a 20% chance of persistent vesicoureteral reflux. CONCLUSIONS: Parents of children with vesicoureteral reflux prefer antibiotic prophylaxis as initial treatment. However, when daily antibiotics and yearly cystography may be required beyond 3 to 4 years, most parents would choose definitive correction. While endoscopic treatment is less effective than surgery, parents prefer endoscopic treatment, most likely because it is less invasive. Also, when compared directly against each other, the majority of parents stated that they would choose endoscopic treatment over surgery, although it has a lower success rate.

Antibiotic Prophylaxis↗
PubMed2000

Racial disparities in access to renal transplantation--clinically appropriate or due to underuse or overuse?

BACKGROUND: Despite abundant evidence of racial disparities in the use of surgical procedures, it is uncertain whether these disparities reflect racial differences in clinical appropriateness or overuse or underuse of inappropriate care. METHODS: We performed a literature review and used an expert panel to develop criteria for determining the appropriateness of renal transplantation for patients with end-stage renal disease. Using data from five states and the District of Columbia on patients who had started to undergo dialysis in 1996 or 1997, we selected a random sample of 1518 patients (age range, 18 to 54 years), stratified according to race and sex. We classified the appropriateness of patients as data on candidates for transplantation and analyzed rates of referral to a transplantation center for evaluation, placement on a waiting list, and receipt of a transplant according to race. RESULTS: Black patients were less likely than white patients to be rated as appropriate candidates for transplantation according to appropriateness criteria based on expert opinion (71 blacks [9.0 percent] vs. 152 whites [20.9 percent]) and were more likely to have had incomplete evaluations (368 [46.5 percent] vs. 282 [38.8 percent], P<0.001 for the overall chi-square). Among patients considered to be appropriate candidates for transplantation, blacks were less likely than whites to be referred for evaluation, according to the chart review (90.1 percent vs. 98.0 percent, P=0.008), to be placed on a waiting list (71.0 percent vs. 86.7 percent, P=0.007), or to undergo transplantation (16.9 percent vs. 52.0 percent, P<0.001). Among patients classified as inappropriate candidates, whites were more likely than blacks to be referred for evaluation (57.8 percent vs. 38.4 percent), to be placed on a waiting list (30.9 percent vs. 17.4 percent), and to undergo transplantation (10.3 percent vs. 2.2 percent, P<0.001 for all three comparisons). CONCLUSIONS: Racial disparities in rates of renal transplantation stem from differences in clinical characteristics that affect appropriateness as well as from underuse of transplantation among blacks and overuse among whites. Reducing racial disparities will require efforts to distinguish their specific causes and the development of interventions tailored to address them.

Adult↗
PubMed2000

Femur length and trisomy 21: impact of gestational age on screening efficiency.

OBJECTIVE: This study assesses two methods used to define relatively short femur in screening for trisomy 21 and examines changes in performance of screening with gestational age. DESIGN: Retrospective analysis of data on menstrual age, femur length (FL) and biparietal diameter (BPD) in 49 trisomy 21 pregnancies and 6069 normal controls. Reference ranges were derived for BPD/FL versus menstrual age and for FL versus BPD. Two methods of defining short femur (BPD/FL and observed-to-expected FL ratio) were examined for false-positive rates and detection rates for trisomy 21 at different gestational ages. RESULTS: In the control group the BPD/FL ratio and its standard deviation decreased with menstrual age. Trisomy 21 was associated with a significantly higher BPD/FL ratio (P < 0.001) and the deviation increased significantly with menstrual age (P < 0.05). Eleven percent of 28 fetuses examined at 15-17 weeks had a BPD/FL above the 95th centile compared with 24% of 21 fetuses examined at 18-20 weeks (P = 0.40). The median observed-to-expected FL ratio in the control group was 1.0 throughout the gestational age range but the standard deviation decreased significantly with menstrual age (P < 0.01). Trisomy 21 was associated with a significantly reduced observed-to-expected FL ratio (P < 0.001) and the deviation increased significantly with menstrual age (P < 0.05). A fixed cut-off of 0.91 for observed-to-expected FL ratio provided a false-positive rate of 12% at 15-17 weeks compared with 6% at 18-20 weeks of gestation (P < 0.001) with detection rates of 29 and 38%, respectively (P = 0.73). CONCLUSION: Irrespective of the definition used to define the condition, relatively short femur is a poor marker for trisomy 21 particularly when the assessment takes place before 18 weeks of gestation.

Adult↗
PubMed2000

The influence of suckling interval on milk production of sows.

The objective of this study was to determine whether sow milk yield per gland could be increased by reducing the interval between suckles (suckling interval). Eighteen sows were allocated at their first farrowing to three treatments comprising litter sizes of 6 or 12 piglets or a cross-suckling treatment that was imposed to increase suckling frequency. The cross-suckled treatment comprised two groups of six piglets each. Each suckling group was allowed to suckle the sow during 30-min intervals each day between d 6 and d 28 of lactation. The suckling interval was shorter (P < .05) for cross-suckled sows than for sows suckling single litters of 6 or 12 piglets during early lactation (d 10 to 14) and late lactation (d 24 to 28). Average piglet growth rate between birth and 28 d of age was greatest (P < .05) for piglets in the single litters of six and lowest for piglets in the cross-suckled treatments. Single litters of 12 piglets had the highest (P < .05) litter growth rates, followed by the cross-suckled litters and then the single litters of six piglets. The concentration of lactose and fat in milk from sows remained relatively stable, although milk from the cross-suckled sows contained more protein in early lactation (P < .05). Milk yield of sows was not significantly increased (P > .05) by the cross-suckle treatment, although during early lactation, milk yield tended to be greater from sows in the cross-suckle treatment than from sows suckling single litters of six (8,920 g/d vs 7,819 g/d, P < .1). The concentration of DNA and total RNA and the RNA:DNA ratio in mammary glands was unaffected by treatment (P > .05). Sows with single litters of 12 piglets had the greatest total DNA in their udders (P < .05). However, individual gland weights were heavier (P < .05) in cross-suckled sows than in sows with single litters of 6 or 12 piglets. Increased suckling frequency seemed to play a role in increased mammary gland weight and milk production during lactation.

Animals↗
PubMed1999

Lack of Borrelia burgdorferi DNA in synovial samples from patients with antibiotic treatment-resistant Lyme arthritis.

OBJECTIVE: To determine whether Borrelia burgdorferi DNA may be detected in synovial tissue from patients with Lyme arthritis who have persistent synovial inflammation after antibiotic treatment. METHODS: Synovial specimens obtained at synovectomy from 26 patients with antibiotic treatment-resistant Lyme arthritis and from 10 control subjects were tested for B burgdorferi DNA using 3 primer-probe sets that target genes encoding outer surface proteins A or B or a flagellar protein (P41) of the spirochete. RESULTS: The 26 patients with Lyme arthritis, who had received antibiotic therapy for a mean total duration of 8 weeks prior to synovectomy, and the 10 control subjects each had negative polymerase chain reaction (PCR) results in synovial samples. When the samples were spiked with approximately 1-10 B burgdorferi, all but 1 had positive PCR results, suggesting that spirochetal DNA could have been detected in most of the unspiked samples if it had been present. CONCLUSION: These results indicate that synovial inflammation may persist in some patients with Lyme arthritis after the apparent eradication of the spirochete from the joint with antibiotic therapy.

Adolescent↗
PubMed1999

Morphological and biochemical responses of Bacillus subtilis to selenite stress.

When introduced into a chemically defined minimal medium supplemented with 1 mM sodium selenite (79 ppm Se(o)), Bacillus subtilis was found to undergo a series of morphological and biochemical adaptations. The morphological changes included the formation of "round bodies" associated with the detoxification of selenite to elemental selenium. Round bodies observed transiently were not apparent during balanced growth of cells adapted previously to selenite-containing medium. Under balanced growth conditions, cell structures similar to "round bodies", could be produced by treating cells with lysozyme. The selenite-induced structural alterations in cells were accompanied by an increase in the content of thioredoxin and the associated enzyme, NADP-thioredoxin reductase. The results suggest that the biovalence transformation of high levels of selenite may involve a dithiol system.

Bacillus subtilis↗
PubMed1999

Comparison of absorbable and nonabsorbable sutures for microsurgical vasovasostomy in rats.

OBJECTIVES: At least 12% of initially patent vasovasostomies (VVs) shut down. Currently, only nonabsorbable sutures are used for VV. A synthetic, slowly absorbing, monofilament polyglactin suture has been developed that retains tensile strength for up to 6 months. We performed a prospective controlled randomized study comparing absorbable and nonabsorbable sutures for rat VVs. METHODS: Bilateral microsurgical VV was performed in three groups of 36 Wistar male rats, with 10-0 nylon, 10-0 polypropylene, and 10-0 polyglactin sutures. Twelve control rats underwent sham operations. Three rats in each group were killed at 2, 6, 12, and 24 weeks. The abdominal end of the vas deferens was transected and the intraluminal fluid examined microscopically for presence of sperm. The segment of the vas deferens containing the anastomosis was excised. Fluid from the testicular end was examined for sperm to confirm spermatogenesis. Patency was confirmed by an antegrade indigo carmine vasogram of the anastomotic segment. Segments were randomly sent for histologic or tensile strength evaluation. RESULTS: The mean tensile strength of the anastomoses performed with nylon was slightly higher than in polypropylene and polyglactin sutures, although the difference was not statistically significant. Polyglactin consistently maintained tensile strength throughout 6 months without significant fluctuations. The mean patency rate in the polyglactin group was 96%, in nylon 81%, and in polypropylene 61%. Although polyglactin had a consistently higher patency rate compared with nonabsorbable sutures, the difference was not statistically significant (P = 0.11) but indicated a strong trend. The occurrence of microscopic sperm granuloma, muscle layer injuries, intimal fibrosis, and adventitial fibrosis of the vas deferens was not significantly different between suture types. CONCLUSIONS: The three suture materials appear equivalent with respect to overall tensile strength of anastomosis; with histologic evaluation, the trend was toward better patency with polyglactin. Polyglactin 10-0 microsurgical suture is a viable alternative to nonabsorbable sutures in microsurgical VVs, although further studies are indicated to assess long-term results.

Animals↗
PubMed1999

Inadvertent ketamine overdose in children: clinical manifestations and outcome.

STUDY OBJECTIVE: We sought to characterize the clinical manifestations, outcome, and etiology of inadvertent ketamine overdose in the emergency department. METHODS: We investigated cases of inadvertent ketamine overdose in children seen in the ED solicited through electronic mail subscription lists or reported to the Institute for Safe Medication Practices. The clinical manifestations, outcome, and reported cause for each case are described. RESULTS: We identified 9 cases of inadvertent ketamine overdose in children treated in the ED. Patients received either 5(n=3), 10(n=5), or 100(n=1) times the intended dose, either by the intramuscular (n=5) or intravenous (n=4) route. All 9 experienced prolonged sedation (3 to 24 hours). Four experienced brief respiratory depression shortly after administration, and assisted ventilation was performed in 2. Two children without respiratory difficulty or hypoxemia were intubated by their physicians as a precaution. In 5 children, the dosing error was not discovered until late in the sedation, often when the child was not waking at the expected time. No adverse outcomes were noted, and all children were normal neurologically on discharge and longer-term follow-up if available. CONCLUSION: No adverse outcomes were noted in 9 healthy children treated in the ED who inadvertently received 5 to 100 times the intended dose of ketamine. Toxicity manifested as prolonged sedation in all 9 and brief respiratory depression in 4. The margin of safety in ketamine overdose may be wide, although less common and more serious outcomes cannot be excluded by this small, self-reported sample.

Anesthetics, Dissociative↗
PubMed1998

Ovarian steroids and stress produce changes in peripheral benzodiazepine receptor density.

Although past research has described changes in the density of the peripheral benzodiazepine receptor in brain and in peripheral organs in response to stressors and steroid hormone exposure, their combined influence had yet to be determined. This study examined the effect of swim-stress as a function of ovarian hormone administration on the binding of an isoquinoline carboxamide derivative, [3H]PK 11195, in brain and peripheral tissues. In olfactory bulb and adrenal gland, stress increased peripheral benzodiazepine receptor density in ovariectomized rats with and without estradiol and progesterone replacement injection, even when compared with unstressed animals treated with hormones, where estradiol + progesterone decreased peripheral benzodiazepine receptor number in olfactory bulb, but estradiol and estradiol + progesterone increased it in adrenal gland. In frontal cortex, stress decreased peripheral benzodiazepine receptor number, an effect that was reversed by estradiol. In hippocampus estradiol decreased peripheral benzodiazepine receptor density in unstressed animals and estradiol + progesterone decreased peripheral benzodiazepine receptor number in unstressed and stressed animals. In cerebellum, stress, estradiol and estradiol + progesterone alone decreased peripheral benzodiazepine receptor density. In uterus of unstressed controls, estradiol + progesterone increased peripheral benzodiazepine receptor density, and stress produced a further increase in steroid-treated females. Stress did not affect peripheral benzodiazepine receptor density in kidney, except in animals that received estradiol + progesterone injections, where swim-stress produced a significant decrease in peripheral benzodiazepine receptor density. Thus, steroid hormones regulate peripheral benzodiazepine receptor density in endocrine organs and brain, and the hormonal state of the organism modifies the peripheral benzodiazepine receptor response to stress in a tissue- and brain region-specific manner, suggesting that the peripheral benzodiazepine receptor may play a pivotal role in an integrated response to stress.

Adrenal Glands↗