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Biomedical subjects

R L Atkinson

Publications and source records attributed to R L Atkinson.

At least 19 recordsLinked to original sources
PubMed2005

Sustained increase in dietary oleic acid oxidation following morning exercise.

OBJECTIVE: We have previously reported that prior exercise increases the oxidation of dietary monounsaturated fat in comparison to rest when the fat is given in a mixed meal 30 min following the completion of exercise. In this study, we determined whether the increase in dietary fat oxidation after exercise persisted when the time between exercise and fatty acid administration was lengthened. DESIGN: Six female subjects (age=24+/-0.1 y, BMI=21+/-1 kg/m2) were recruited for a total of six visits each. During three visits, a stationary cycle exercise session (1250 kJ) was performed at 65% VO2 peak in a whole-body calorimeter; while during three other visits, exercise was replaced with rest. Subjects received [1-13C]oleate and [d31]palmitate with a different meal at each visit: breakfast, lunch, and dinner. RESULTS: Dietary oleate oxidation following prior rest did not differ between dose times and was 36+/-3, 42+/-5, and 42+/-3% for the 13 h following breakfast, lunch, and dinner. Prior exercise resulted in greater oleate oxidation following all dose times than prior rest (P<0.01) being 52+/-4, 64+/-3, and 53+/-3% for the breakfast, lunch, and dinner dose. The oxidation was significantly greater following lunch than the other dose times (P<0.05). Prior exercise (1250 kJ) did not result in greater oxidation of palmitate; however, oxidation following prior exercise increased with later dose times (13+/-2, 23+/-2, and 23+/-3% for breakfast, lunch, and dinner; P<0.05) and following rest (18+/-2, 22+/-2, and 27+/-2% for breakfast, lunch, and dinner; P<0.005). CONCLUSIONS: The increase in oleate oxidation when administered after early morning exercise was found to persist for all three meals of the day, with the greatest effect occurring for the lunch meal. Palmitate oxidation, while apparently resistant to the effects of 1250 kJ of prior exercise, increases when administered later in the day, suggesting a diurnal variation in the oxidation of dietary fatty acids. These results demonstrate that prior exercise selectively alters the partitioning of dietary fatty acids. Furthermore, these findings demonstrate additional benefits of substituting monounsaturated for saturated fatty acids in the diet.

Adult↗
PubMed2005

Human adenovirus-36 is associated with increased body weight and paradoxical reduction of serum lipids.

BACKGROUND: Human adenovirus-36 (Ad-36) increases adiposity and paradoxically lowers serum cholesterol and triglycerides in chickens, mice, and non-human primates. The role of Ad-36 in human obesity is unknown. OBJECTIVES: To determine the prevalence of Ad-36 antibodies in obese and nonobese humans. To evaluate the association of Ad-36 antibodies with body mass index (BMI) and serum lipids. DESIGN: Cohort study. Volunteers from obesity treatment programs, communities, and a research study. SUBJECTS: Obese and nonobese volunteers at the University of Wisconsin, Madison, WI, and the Bowen Center, Naples, Florida. Obese and thin volunteer research subjects and 89 twin pairs at Columbia University, New York. INTERVENTIONS: Study 1: 502 subjects; serum neutralization assay for antibodies to Ad-2, Ad-31, Ad-36, and Ad-37; serum cholesterol and triglycerides assays. Study 2: BMI and %body fat in 28 twin pairs discordant for Ad-36 antibodies. MAIN OUTCOME MEASURES: Presence of antibodies to adenoviruses, BMI, serum cholesterol and triglycerides levels. RESULTS: Significant (P < 0.001) association of obesity and positive Ad-36 antibody status, independent of age, sex, and collection site. Ad-36 antibodies in 30% of obese, 11% of nonobese. Lower serum cholesterol and triglycerides (P < 0.003) in Ad-36 antibody-positive vs -negative subjects. Twin pairs: antibody-positive twins had higher BMIs (24.5+/-5.2 vs 23.1+/-4.5 kg/m2, P < 0.03) and %body fat (29.6+/-9.5% vs 27.5+/-9.9%, P < 0.04). No association of Ad-2, Ad-31, or Ad-37 antibodies with BMI or serum lipids. CONCLUSIONS: Ad-36 is associated with increased body weight and lower serum lipids in humans. Prospective studies are indicated to determine if Ad-36 plays a role in the etiology of human obesity.

Adenovirus Infections, Human↗
PubMed2004

Safety profile of conjugated linoleic acid in a 12-month trial in obese humans.

Conjugated linoleic acid (CLA) is marketed in numerous commercially available dietary supplements, but few studies have looked at the long-term safety of this product. The current study evaluated the safety of one CLA product (Clarinol) over a one-year period in obese humans who were generally healthy. This was a randomized, double-blind study consisting of three phases in which subjects were given 6 g/day of CLA or placebo. Phase 1 was a low calorie diet (13 kcal/kg desirable weight) for 12 weeks or until 10-20% of initial body weight was lost. In phase 2, from weeks 12 to 28, subjects were re-fed a diet providing 25-30 kcal/kg of desirable body weight. Phase 3 was open label, with subjects from both groups taking CLA from weeks 28 to 52. At biweekly visits, subjects completed a questionnaire evaluating side effects and adverse events. Blood was taken for assay of liver function, glucose, insulin, serum lipids, blood counts, and general chemistry. Overall, body composition did not differ between groups. Laboratory tests showed no adverse effects of CLA. Adverse events and side effects were less in the CLA group compared to placebo. We conclude that CLA as Clarinol is safe for use in obese humans for at least one year.

Adult↗
PubMed2001

Transmissibility of adenovirus-induced adiposity in a chicken model.

BACKGROUND: We previously reported that human adenovirus Ad-36 induces adiposity and paradoxically lower levels of serum cholesterol (CHOL) and triglycerides (TG) in animals. OBJECTIVE: To evaluate the transmissibility of Ad-36 and Ad-36 induced adiposity using a chicken model. DESIGN: Experiment 1--four chickens were housed (two per cage) and one from each cage was inoculated with Ad-36. Duration of presence of Ad-36 DNA in the blood of all chickens was monitored. Experiment 2--two groups of chickens were intranasally inoculated with Ad-36 (infected donors, I-D) or media (control donors, C-D). Blood drawn 36 h later from I-D and C-D groups was inoculated into wing veins of recipient chickens (infected receivers, I-R, and control receivers, C-R, respectively). On sacrifice, 5 weeks post-inoculation, blood was drawn, body weight noted and visceral fat was separated and weighed. RESULTS: Experiment 1--Ad-36 DNA appeared in the blood of the inoculated chickens and that of uninoculated chickens (cage mates) within 12 h of inoculation and the viral DNA persisted up to 25 days in the blood. Experiment 2--compared with C-D, visceral and total body fat were significantly greater and CHOL significantly lower for the I-D and I-R. TG were significantly lower for the I-D. Ad-36 was isolated from 12 out of 16 blood samples of the I-D that were used for inoculating I-R chickens. Ad-36 DNA was present in the blood and the adipose tissue of the I-D and I-R but not in the skeletal muscles of animals selected randomly for testing. CONCLUSION: As seen in experiment 1, Ad-36 infection can be transmitted horizontally from an infected chicken to another chicken sharing the cage. Additionally, experiment 2 demonstrated blood-borne transmission of Ad-36-induced adiposity in chickens. Transmissibility of Ad-36-induced adiposity in chicken model raises serious concerns about such a possibility in humans that needs further investigation.

Adenovirus Infections, Human↗
PubMed2001

Neuroendocrine and pharmacological manipulations to assess how caloric restriction increases life span.

As part of an effort to review current understanding of the mechanisms by which caloric restriction (CR) extends maximum life span, the authors of the present review were requested to develop a list of key issues concerning the potential role of neuroendocrine systems in mediating these effects. It has long been hypothesized that failure of specific neuroendocrine functions during aging leads to key age-related systemic and physiological failures, and more recently it has been postulated that physiological neuroendocrine responses to CR may increase life span. However, although the acute neuroendocrine responses to fasting have been well studied, it is not clear that these responses are necessarily identical to those observed in response to the chronic moderate (30% to 50% reduction) CR that increases maximum life span. Therefore the recommendations of this panel fall into two categories. First, further characterization of neuroendocrine responses to CR over the entire life span is needed. Second, rigorous interventional studies are needed to test the extent to which neuroendocrine responses to CR mediate the effects of CR on life span, or alternatively if CR protects the function of essential neuroendocrine cells whose impairment reduces life span. Complementary studies using rodent models, nonhuman primates, and humans will be essential to assess the generality of elucidated mechanisms, and to determine if such mechanisms might apply to humans.

Animals↗
PubMed2000

Direct quantification of AD-36 adenovirus DNA by capillary electrophoresis with laser-induced fluorescence.

An adenovirus, AD-36, has been linked to human adiposity and a sensitive and reliable quantitative method is required to assess AD-36 viral loads. This report describes direct detection of AD-36 viral DNA, which is the first method to quantitate DNA without amplification. Total genomic DNA is hybridized with an AD-36 specific fluorescently labeled probe and analyzed by capillary electrophoresis with laser-induced fluorescence. The minimum detectable quantity is 10.3 ng/ml, corresponding to 282 copies of AD-36 with a precision of 1-6%. These results indicate that direct detection with capillary electrophoresis with laser-induced fluorescence (CE-LIF) is a reliable and sensitive method for quantifying AD-36 viral DNA.

Adenoviridae↗
PubMed2000

Conjugated linoleic acid: implications for human health.

Conjugated linoleic acid (CLA) is being sold as a panacea that has the capability of reducing or eliminating cancer, preventing heart disease, improving immune function, and altering body composition to treat obesity or build lean body mass. Unfortunately, there has been very little published human research on CLA. This review will examine the literature on CLA and discuss the animal research on which the above claims are made. The limited human studies will be presented with an evaluation of the potential uses of CLA for human health and disease.

Adjuvants, Immunologic↗
PubMed2000

Self-help weight loss versus a structured commercial program after 26 weeks: a randomized controlled study.

PURPOSE: There have been few randomized controlled trials of commercial weight-loss programs. This ongoing study compares the effects of a self-help program and a commercial program on weight loss and other measures of obesity in overweight and obese men and women. SUBJECTS AND METHODS: We report the results of the first 26 weeks of a multicenter, randomized, 2-year study of 423 subjects who had a body mass index of 27 to 40 kg/m(2). Subjects were randomly assigned to either a self-help program, consisting of two 20-minute sessions with a nutritionist and provision of printed materials and other self-help resources, or to attendance at meetings of a commercial program (Weight Watchers). Outcome measures were changes in body weight, body mass index, waist circumference, and body fat. Changes in serum homocysteine levels were measured in a subsample of participants during the first 12 weeks. RESULTS: After 26 weeks, subjects in the commercial program, as compared with those in the self-help program, had greater decreases in body weight [mean (+/- SD) -4.8+/-5.6 vs -1.4+/-4.7 kg] and body mass index (-1.7+/-1.9 vs -0.5+/-1.6 kg/m(2), both P<0.001) in intention-to-treat analyses. Among subjects measured at week 26, mean waist circumference (-4.3+/-10.5 vs -0.7+/-12.7 cm) and fat mass (-3.8 +/-7.0 vs -1.5+/-7.6 kg, both P<0.05) also decreased more among subjects in the commercial program. Mean serum homocysteine levels improved in the commercial program compared with self-help (-0.5+/-1.3 vs 0.9+/-1.8 microM, P<0.05). CONCLUSIONS: A structured commercial weight-loss program is more likely to be effective for managing moderately overweight patients than brief counseling and self-help.

Adult↗
PubMed2000

Increased adiposity in animals due to a human virus.

BACKGROUND: Four animal models of virus-induced obesity including adiposity induced by an avian adenovirus have been described previously. This is the first report of adiposity induced in animals by a human virus. OBJECTIVE: We investigated the adiposity promoting effect of a human adenovirus (Ad-36) in two different animal models. DESIGN: Due to the novel nature of the findings we replicated the experiments using a chicken model three times and a mammal model once. In four separate experiments, chickens and mice were inoculated with human adenovirus Ad-36. Weight matched groups inoculated with tissue culture media were used as non-infected controls in each experiment. Ad-36 inoculated and uninfected control groups were housed in separate rooms under biosafety level 2 or better containment. The first experiment included an additional weight matched group of chickens that was inoculated with CELO (chick embryo lethal orphan virus), an avian adenovirus. Food intakes and body weights were measured weekly. At the time of sacrifice blood was drawn and visceral fat was carefully separated and weighed. Total body fat was determined by chemical extraction of carcass fat. RESULTS: Animals inoculated with Ad-36 developed a syndrome of increased adipose tissue and paradoxically low levels of serum cholesterol and triglycerides. This syndrome was not seen in chickens inoculated with CELO virus. Sections of the brain and hypothalamus of Ad-36 inoculated animals did not show any overt histopathological changes. Ad-36 DNA could be detected in adipose tissue, but not skeletal muscles of randomly selected animals for as long as 16 weeks after Ad-36 inoculation. CONCLUSIONS: Data from these animal models suggest that the role of viral disease in the etiology of human obesity must be considered.

Adenovirus Infections, Human↗
PubMed2000

An association of elevated serum gonadotropin concentrations and Alzheimer disease?

Alzheimer disease affects almost 4 million Americans and costs $65 billion annually. The disease is more common in women than in men, and studies suggest that oestrogen may have a protective effect. Oestrogen replacement lowers circulating concentrations of gonadotropins. When gonadotropins are added to rat granulosa cells in culture, the number of low density lipoprotein (LDL) receptors and the rate of uptake of low density lipoprotein increases. Many proteins found in Alzheimer disease plaques are ligands for low density lipoprotein receptors (LDLR) on central nervous system (CNS) neurones. This study evaluated whether gonadotropins may be associated with Alzheimer disease. Circulating concentrations of follicle stimulating hormone (FSH) and luteinizing hormone (LH) levels in 40 male residents of long-term care facilities with the primary diagnosis of dementia were compared to 29 age-matched controls. Serum concentrations of FSH and LH were significantly higher in dementia patients. We speculate they may play an aetiologic role in the deposition of abnormal proteins, particularly those associated with low density lipoprotein receptors, in CNS neurones.

Alzheimer Disease↗
PubMed2000

Impact of obesity on health-related quality of life in patients with chronic illness.

OBJECTIVE: To determine the association between overweight and obesity and health-related quality of life (HRQOL) in patients with chronic conditions typical of those seen in general medical practice, after accounting for the effects of depression and medical comorbidities. DESIGN: Cross-sectional analysis of data from the Medical Outcomes Study. SETTING: Offices of physicians practicing family medicine, internal medicine, endocrinology, cardiology, and psychiatry in three U.S. cities. PATIENTS: We surveyed 2,931 patients with chronic medical and psychiatric conditions. The patients completed a self-administered questionnaire at enrollment and had complete data on height and weight. MEASUREMENTS AND MAIN RESULTS: Body mass index (BMI), chronic medical conditions, and depression were obtained by structured interview. Health-related quality of life was measured by the SF-36 Health Survey. Patients who were overweight (BMI 25.0-29.9 kg/m2), patients with class I obesity (BMI 30.0-34.9 kg/m2), and patients with class II-III obesity (BMI > or = 35 kg/m2) had significantly lower adjusted physical function scores (by 3.4, 7.8, and 13.8 points, respectively) compared with nonoverweight patients. Patients with class I and class II-III obesity also had significantly lower adjusted general health perceptions scores (by 2.8 and 4.4 points, respectively) and lower adjusted vitality scores (by 4.0 and 7.1 points, respectively), compared with nonoverweight patients. No significant differences between nonoverweight, overweight, and obese patients were observed for the mental health scale. Women with elevated BMI had significantly lower HRQOL scores compared with the scores of obese men in several domains. Additionally, blacks with elevated BMI had significantly lower scores than whites in several domains of HRQOL. CONCLUSIONS: Overweight and obesity have the largest association with physical function measures. Recent national standards, which have lowered the threshold for defining overweight, identify patients who are more likely to have clinically significant reductions in HRQOL and functional impairment.

Adult↗
PubMed2000

The comparative efficacy of intravenous cefotaxime and trimethoprim/sulfamethoxazole in preventing infection after neurosurgery: a prospective, randomized study. Brisbane Neurosurgical Infection Group.

The objective of the investigation was to determine the comparative efficacy of cefotaxime versus trimethoprim-sulfamethoxazole in the prophylaxis of patients undergoing neurosurgical procedures. In this prospective randomized open study, 780 adult patients undergoing elective craniotomy, shunt surgery or stereotactic surgery were randomized to receive preoperative cefotaxime (1 g) or trimethoprim-sulfamethoxazole (160 mg trimethoprim, 800 mg sulfamethoxazole) as prophylaxis: 613 patients were available for analysis, of whom 315 received cefotaxime and 298 received trimethoprim-sulfamethoxazole. Forty-two patients (6.9%) experienced 49 postoperative infections, with no significant difference between treatment groups. The most common infections unrelated to neurosurgery were urinary tract infections (17 cases) and pneumonia (seven cases). Fifteen neurosurgical infections occurred, comprising 11 wound infections, two shunt infections and two cerebral abscesses. Neurosurgical infection rates were similar in the cefotaxime group (2.5%) and the trimethoprim-sulfamethoxazole group (2.3%). We concluded cefotaxime and trimethoprim-sulfamethoxazole administered as single dose prior to neurosurgery are equally effective in controlling neurosurgical infection and postoperative infection at remote sites.

Adult↗
PubMed1999

Cerebrovascular biomodelling: a technical note.

BACKGROUND: Recently computed tomographic angiography (CTA) and MR angiography (MRA) have been used to image cerebrovascular structures. Although CTA and MRA are accurate and sensitive imaging modalities, limitations have been identified in relation to image interpretation. Stereolithographic (SL) biomodelling is a new technology that allows three-dimensional (3D) CT and MR data to be used to accurately manufacture solid plastic replicas of anatomical structures. A prospective trial of SL biomodelling in cerebrovascular surgery has been performed to investigate the feasibility and clinical utility of this new display medium. METHODS: Fifteen patients with cerebral aneurysms and 1 patient with a cerebral arteriovenous malformation (AVM) were selected. 3D CT and/or MR angiograms were acquired and 19 solid anatomical biomodels manufactured using the rapid prototyping technology of stereolithography. The biomodels were used for patient education, diagnosis, operative planning and surgical navigation. RESULTS: The biomodels replicated the CTA and MRA source data. The accuracy of one biomodel was verified by comparison with a post mortem specimen, which corresponded exactly in the x and y planes but differed by 2 mm in the z plane. The ability to closely study an overview of complex cerebrovascular anatomy from any perspective on a solid biomodel was reported to enhance the surgeon's understanding, particularly when conventional images were equivocal. Cerebrovascular biomodels were found to be useful when positioning the patient's head for surgery, for selecting the best aneurysm clip and for the simulation of clipping. Patient informed consent was anecdotally improved. Disadvantages of the technology were the cost and manufacturing time. CONCLUSIONS: Cerebrovascular biomodelling may have utility in complex cases or when the standard imaging is felt to be equivocal.

Adult↗
PubMed1999

Stereolithographic biomodelling in cranio-maxillofacial surgery: a prospective trial.

Stereolithographic (SL) biomodelling is a new technology that allows three-dimensional (3-D) computed tomography (CT) data to be used to manufacture solid plastic replicas of anatomical structures (biomodels). A prospective trial with the objective of assessing the utility of biomodelling in complex surgery has been performed. Forty-five patients with craniofacial, maxillofacial, skull base cervical spinal pathology were selected. 3-D CT or MR scanning was performed and the data of interest were edited and converted into a form acceptable to the rapid prototyping technology SL. The data were used to guide a laser to selectively polymerize photosensitive resin to manufacture biomodels. The biomodels were used by surgeons for patient education, diagnosis and operative planning. An assessment protocol was used to test the hypothesis that 'biomodels in addition to standard imaging had greater utility in the surgery performed than the standard imaging alone'. Biomodels significantly improved operative planning (images 44.09%, images with biomodel 82.21%, P < .01) and diagnosis (images 65.63%, images with biomodel 95.23%, P < .01). Biomodels were found to improve measurement accuracy significantly (image measurement error 44.14%, biomodel measurement error 7.91%, P < .05). Surgeons estimated that the use of biomodels reduced operating time by a mean of 17.63% and were cost effective at a mean price of $1031 AUS. Patients found the biomodels to be helpful for informed consent (images 63.53%, biomodels 88.54%, P < .001). Biomodelling is an intuitive, user-friendly technology that facilitated diagnosis and operative planning. Biomodels allowed surgeons to rehearse procedures readily and improved communication between colleagues and patients.

Cephalometry↗
PubMed1999

Initial weight loss as a predictor of response to obesity drugs.

BACKGROUND: Initial weight loss has been used as a predictor of long-term response to obesity drugs. Discontinuation of drugs has been recommended if weight loss is not > or =1.81 kg (4 lb) in the first month of treatment. OBJECTIVE: We compared the weight loss response at 6 months of patients losing > or =1.81 kg (responders) vs. < 1.81 kg (non-responders) in the first month of treatment with the combination of fenfluramine and phentermine. DESIGN: Outcomes at 6 months in 975 patients treated in a comprehensive program of phentermine (15-30 mg/d) d,l-fenfluramine (20-60 mg/d), were compared for responders vs. non-responders. RESULTS: In the total population, first month weight loss highly correlated with % reduction in body mass index (BMI) after 6 months of treatment (P<0.001). The reduction in baseline BMI after 6 months treatment was greater for the responders (15.9% vs. 10%, P<0.02). However, the North American Association for the Study of Obesity (NAASO) guidelines for drug treatment of obesity state that a 5% weight loss produces significant health benefits, and may be used as a criteria for success. At 6 months, 76%, 37% and 14% of the non-respondents had lost > or = 5%, > or = 10% and > or = 15% of baseline BMI, respectively. After 6 months treatment the reductions in serum cholesterol, triglycerides and LDL-cholesterol were 0.55, 0.31 and 0.42 mmol/L, respectively, (P< or =0.006), for the non-responders. Adverse effects after 6 months of treatment and the dropout rates after 1 y of treatment were not significantly different for the two groups. CONCLUSIONS: Although, the first month weight loss predicted the long-term response to phen-fen treatment, it was inadequate in identifying the non-responders and may unnecessarily preclude potential beneficiaries of the treatment.

Adult↗
PubMed1999

Biomodel-guided stereotaxy.

OBJECTIVES: To simplify the practice of stereotactic surgery by using an original method, apparatus, and solid anatomic replica for trajectory planning and to validate the method and apparatus in a laboratory and clinical trial. METHODS: The patient is marked with fiducials and scanned by using computed tomography or magnetic resonance imaging. The three-dimensional data are converted to a format acceptable to stereolithography. Stereolithography uses a laser to polymerize photosensitive resin into a solid plastic model (biomodel). Stereolithography can replicate blood vessels, soft tissue, tumor, and bone accurately (<0.8 mm). A stereotactic apparatus is referenced to fiducials replicated in the biomodel. The trajectory for the intervention is determined and saved. The apparatus is attached to the patient fiducials, and the intervention is replicated. RESULTS: Three types of apparatus (template, Brown-Roberts-Wells frame, and D'Urso frame) were tested on phantoms and patients requiring the excision/biopsy of tumors. The localization errors determined from the phantom studies were template, 0.82 mm; Brown-Roberts-Wells frame, 1.17 mm; and D'Urso frame, 0.89 mm. The surgeons reported that clinical use of the template and D'Urso frame was accurate and ergonomic. The Brown-Roberts-Wells frame was more difficult to use and somewhat inaccurate. CONCLUSION: Biomodel-guided stereotaxy has significant advantages. It is performed quickly; it is based on simple, intuitive methodology; it enhances visualization of anatomy and trajectory planning; it enhances patient understanding; it uses inexpensive equipment; it does not require rigid head fixation; and it has greater versatility than known techniques. Disadvantages are biomodel cost and a manufacturing time of 12 to 24 hours.

Biopsy↗