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Biomedical subjects

D Burton

Publications and source records attributed to D Burton.

At least 73 records · Page 4Linked to original sources
PubMed1993

Health behavior changes through television: the roles of de facto and motivated selection processes.

We assess the role played by two types of self-selection in accounting for the influence of a television series on smoking cessation. De facto selection is based on respondents' regular channel viewing habits that can expose them to the series. Motivated self-selection takes place when viewers deliberately select to watch television programming because it meets their desire to quit smoking. Self-selection also can be viewed as a methodological artifact, spuriously accounting for the association between the airing of the series and smoking cessation among the target audience. Subjects were a probability sample of Chicago smokers who regularly watch the evening news on one of the network channels. The intervention was a televised self-help smoking cessation program broadcast on one of the network channels over 20 days. Using nested covariance structure models for the analysis, we conclude that 1) de facto selection had no influence on exposure to the program; 2) motivated selection had no influence on exposure to the program; 3) the program reduced smoking; and 4) this effect cannot be attributed solely to the methodological artifact of self-selection, although motivation to quit smoking did have the strongest influence on attempts to quit.

Adolescent↗
PubMed1992

A comparison of methods of measuring chromatic activity in the integument of a teleost.

1. Pallor induced by noradrenalin (5 x 10(-7) mol/kg) injection of dark Pseudopleuronectes americanus was measured as increase in skin reflectance and the degree of melanosome aggregation determined. 2. Mean skin reflectance increased approximately 30% on the Munsell neutral value scale. 3. At maximal mean reflectance, melanosomes were fully aggregated in most epidermal melanophores, but displayed more variable aggregation in dermal melanophores. 4. Individual reflectance estimates did not provide consistent indications of melanosome aggregation at maximum pallor. 5. The relative merits of reflectance and cellular methods of estimating melanophore activity are discussed with particular reference to this species.

Animals↗
PubMed1992

Skeletal muscle metabolism in the chronic fatigue syndrome. In vivo assessment by 31P nuclear magnetic resonance spectroscopy.

BACKGROUND: Previous study of patients with chronic fatigue syndrome (CFS) has demonstrated a markedly reduced dynamic exercise capacity, not limited by cardiac performance and in the absence of clinical neuromuscular dysfunction, suggesting the possibility of a subclinical defect of skeletal muscle. METHODS: The in vivo metabolism of the gastrocnemius muscles of 22 CFS patients and 21 normal control subjects was compared during rest, graded dynamic exercise to exhaustion and recovery, using 31P nuclear magnetic resonance (NMR) spectroscopy to reflect minute-to-minute intracellular high-energy phosphate metabolism. RESULTS: Duration of exercise was markedly shorter in the CFS patients (8.1 +/- 2.8 min) compared with the normal subjects (11.3 +/- 4.3 min) (p = 0.005). There were large changes in phosphocreatine (PCr), inorganic phosphate (Pi), and pH from rest to clinical fatigue in all subjects, reflecting the high intensity of the exercise. The temporal metabolic patterns were qualitatively similar in the CFS patients and normal subjects. There were early and continuous changes in PCr and Pi that peaked at the point of fatigue and rapidly reversed after exercise. In contrast, pH was relatively static in early exercise, not declining noticeably until 50 percent of total exercise duration was achieved, and reaching a nadir at 2 min postexercise, before rapidly reversing. There were no differences in pH at rest (7.08 +/- 0.04 vs 7.10 +/- 0.04), exhaustion (6.85 +/- 0.17 vs 6.76 +/- 0.17) or early (6.64 +/- 0.25 vs 6.56 +/- 0.24) or late recovery (7.09 +/- 0.04 vs 7.10 +/- 0.05), CFS patients vs normal subjects, respectively (NS). Neither were there intergroup differences (NS) in PCr or Pi. Although, quantitatively, the changes in PCr, Pi, and pH were marked and similar in both groups from rest to exhaustion, the changes all occurred much more rapidly in the CFS patients. Moreover, adenosine triphosphate (ATP) was significantly (p = 0.007) less at exhaustion in the CFS group. CONCLUSIONS: Patients with CFS and normal control subjects have similar skeletal muscle metabolic patterns during dynamic exercise and reach similar clinical and metabolic end points. However, CFS patients reach exhaustion much more rapidly than normal subjects, at which point they also have relatively reduced intracellular concentrations of ATP. These data suggest a defect of oxidative metabolism with a resultant acceleration of glycolysis in the working skeletal muscles of CFS patients. This metabolic defect may contribute to the reduced physical endurance of CFS patients. Its etiology is unknown. Whether CFS patients' overwhelming tiredness at rest has a similar metabolic pathophysiology or etiology also remains unknown.

Adenosine Triphosphate↗
PubMed1992

Treatment effectiveness outcome research in adult partial hospitalization.

The pilot study at Charter Kingwood was designed as an integral part of continuous quality improvement. Research focused on patient appropriateness and outcome treatment results. The Day Therapy Appropriateness Scale was administered along with pre and post tests of the Index of Self Esteem (ISE) and General Contentment Scale (GCS). Other instruments included a Patient Satisfaction Survey and alumni quarterly follow-up checklist letter. The outcome study demonstrates that patients were appropriately placed in treatment and improved with treatment. Results showed that patients improved 20% after 2 weeks of intensive group therapies. The Patient Satisfaction Survey had 17 items and 4 categories to select degrees of satisfaction or dissatisfaction with the overall program, staff, therapy groups, and individualized treatment goals. Results supported a 90% overall satisfaction with services provided. An alumni quarterly follow-up emphasizing postdischarge planning and aftercare verified that 96.3% of participants benefited from the program, 82% participated in aftercare, and 98.3% would recommend significant others for treatment.

Adult↗
PubMed1992

In vivo skeletal muscle metabolism during dynamic exercise and recovery: assessment by nuclear magnetic resonance spectroscopy.

BACKGROUND: The purpose of this study was to define temporally phosphorus metabolism and pH in the gastrocnemius muscles of 21 normal adult subjects during rest, dynamic exercise to exhaustion, and early and late recovery. METHODS: In vivo nuclear magnetic resonance spectroscopy. RESULTS: At rest, the ratio of phosphocreatine to the alpha peak of ATP averaged 2.26 +/- 0.25, the inorganic phosphate to ATP ratio averaged 0.31 +/- 0.08 and pH averaged 7.10 +/- 0.04. The phosphorus metabolites exhibited immediate and progressive changes with exercise, reaching their minimum (phosphocreatine, 0.95 +/- 0.41) or maximum (inorganic phosphate, 1.95 +/- 0.75) values at exhaustion, after an average exercise of 11 +/- 4 mins. In contrast, pH changed slowly during early exercise, but fell abruptly thereafter and averaged 6.76 +/- 0.17 at exhaustion. Phosphocreatine and inorganic phosphate began to return rapidly towards preexercise values immediately on cessation of exercise. However, pH declined further in the period immediately following cessation of exercise, reaching a nadir of 6.56 +/- 0.24 an average of 2 mins into recovery. Exercise duration did not correlate highly with any metabolic variable. CONCLUSIONS: The data support the concept that the metabolic physiology underlying physical exhaustion of dynamic exercising muscle is multifactorial. The post exercise drop in pH also suggests that normal subjects have a greater contribution to high energy phosphate production from glycolysis, as opposed to oxidative metabolism, in early recovery.

Acid-Base Equilibrium↗
PubMed1991

Evidence for spontaneous neuro-melanophore activity in Pseudopleuronectes americanus (Teleostei; Pleuronectiformes) during total darkness.

In total darkness, melanophores of much of the integumentary pattern of Pseudopleuronectes americanus display intermediate melanosome distribution, whilst the alpha-adrenoceptor antagonist phentolamine evokes their complete dispersion. The intermediate condition is not attained in total darkness in locally decentralized melanophores. It is proposed that, in the absence of photic stimulation, spontaneous neural activity sustains a partial melanosome aggregation in this species.

Animals↗
PubMed1991

Availability of tobacco products at stores located near public schools.

The nearby store is an obvious major site where adolescents obtain tobacco products. We investigated availability of tobacco products to adolescents at those stores located closest to public junior high and high schools by using 3 novel methods: (1) interviewing store personnel; (2) recording types and location of tobacco products, promotional items, and the legal age warning signs within stores; and (3) observing purchasing behavior. Store personnel were interviewed at randomly selected Southern California stores (n = 36) and Illinois stores (n = 12). Results showed that store personnel used tobacco at twice the rate of the general public, and that they often use tobacco while working at the store. Promotional advertisements were present at many stores, while tobacco use legal age signs were posted at few stores. Approximately 50% of the store personnel admitted that they would sell to minors, and many reported that they had seen teenagers using tobacco near the stores. Several apparently illegal purchases were observed. Tobacco use prevention program and policy implications are discussed.

Adolescent↗
PubMed1990

Adolescents' first and most recent use situations of smokeless tobacco and cigarettes: similarities and differences.

This study compared first and most recent use situations of adolescent smokeless tobacco experimenters with those of adolescent cigarette experimenters. Structured, open-ended interviews were conducted with 320 seventh and tenth grade youths in 16 Southern California schools. Students were categorized as nonusers (those who had never experimented with any tobacco product), minimal experimenters (those who had experimented with smokeless tobacco or cigarettes between 1 and 9 times), and persistent experimenters (those who had experimented with smokeless tobacco or cigarettes 10 or more times). The situations reported by smokeless tobacco were similar to those reported by cigarette experimenters. The most important differences between the two groups are highlighted. In particular, smokeless tobacco users seemed less concerned about negative social consequences of use than cigarette smokers. In addition, nonusers' observations of use and implications for prevention and cessation are discussed.

Adolescent↗
PubMed1990

Peer-group association and adolescent tobacco use.

Mosbach & Leventhal (1988) examined the relation of cigarette smoking to peer-group identification in rural Wisconsin adolescents. They found that among dirts (problem-prone youth), regulars (average youth), hot-shots (good social or academic performers), and jocks (athletes), youth most likely to smoke were dirts and hot-shots. We performed a replication with a Southern California cohort and also for use of smokeless tobacco. We hypothesized that jocks would be the main users of smokeless tobacco. We identified the same groups and an additional one, skaters (skateboarders or surfers). As Mosbach & Leventhal found, cigarettes were used most by dirts. Contrary to their results, but consistent with other research, we found that hot-shots were least likely to smoke. Contrary to our prediction, we found that skaters and dirts were more likely to use smokeless tobacco than were jocks. Our data show that both tobacco forms are used by problem-prone youth.

Adolescent↗
PubMed1990

Gallbladder contractility in patients with spinal cord injuries: a sonographic investigation.

Approximately 30% of all patients who have spinal cord injuries have gastrointestinal symptoms. One cause is gallstone disease; indeed the literature suggests that gallstones are more common in patients with spinal cord injuries because these patients have impaired contractility of the gallbladder with a reduced ejection fraction. To test this hypothesis, we obtained gallbladder sonograms in 30 patients with spinal cord injuries (16 quadriplegics and 14 paraplegics) and in 32 uninjured age-matched control subjects. Four patients and four asymptomatic control subjects had gallstones and were excluded. The remaining 26 patients and 28 control subjects fasted for 12 hr. Longitudinal and transverse sonograms of the gallbladder were made immediately before the ingestion of 25 g of fat, and at 10, 20, 30, 45, and 60 min thereafter. Gallbladder volumes were measured by using the ellipsoid method. Resting and residual volumes and the emptying times were determined and the ejection fractions were calculated. The ejection fractions were significantly lower (p = .003) in the patients than in the control subjects because the resting volumes were lower than in the control subjects (p = .013). However, the emptying times and residual volumes were the same in the two groups. We conclude that gallbladder contractility is normal in patients with spinal cord injuries and that the lower ejection fraction found in such patients is due to a smaller resting volume.

Adult↗
PubMed1989

Rapid, simple identification of individual osteoblastic cells and their specific products by cell blotting assay.

Biochemical and molecular biological studies of osteoblastic cell function and hormonal regulation are frequently confounded by the inherent cellular heterogeneity and phenotypic instability of existing in vitro and in vivo model systems. A new technique (derived from Western blotting or antibody-based detection of protein molecules bound to nitrocellulose paper) is described for identification of individual cells which synthesize osteoblast-specific gene products (bone Gla-protein, type I collagen, and alkaline phosphatase) or produce cAMP in response to parathyroid hormone (PTH) or isoproterenol. Dispersed primary neonatal rat calvariae or osteogenic sarcoma cells were "plated" on Immobilon-P (a hydrophobic transfer membrane with very high protein-binding capacity) for 30 minutes to several hours, followed by agonist treatment, formalin fixation, hematoxylin staining, and immunostaining with a battery of antibodies specific for osteoblastic products. Individual cells and their secretory zones were visualized by light microscopy and counted. Treatment with PTH with or without isoproterenol resulted in increases in the percentages of osteoblastic cells elaborating cAMP, as well as the intensity of immunostaining, but had no effects on MCF-7 cells, a nonosteoblastic breast carcinoma control line. The percentage of cells within each primary osteoblastic cell population isolated or rat osteogenic sarcoma cell clone (G2 or C12) that elaborated bone-specific proteins or that generated cAMP in response to PTH varied with time and the individual cellular preparation, reconfirming the cellular heterogeneity of these systems. This method, in conjunction with techniques such as in vitro hybridization, should prove useful in characterizing discrete osteoblastic bone cell subpopulations and in clarifying mechanisms of hormonal regulation by local and systemic agents.

Alkaline Phosphatase↗
PubMed1989

Media manipulation of adolescents' personal level judgements regarding consequences of smokeless tobacco use.

Videotapes were developed to try to impact on personal level judgements of concern and risk in the context of smokeless tobacco use, a growing substance use problem in adolescents. In a within-and-between-subjects design, convincingness (i.e., dramatic portrayal) of the videotaped message (high and low) and perceived probability of consequences portrayed in the message (high and low) were manipulated.

Adolescent↗
PubMed1988

Unique subset of thymic epithelial cells defined by the expression of a novel neuroendocrine antigen.

Murine monoclonal antibodies (MoAbs) were produced against a rat medullary thyroid carcinoma to identify neuroendocrine differentiation antigens. One of these antibodies (1D4) identified a novel 62- to 69-kDa antigen expressed by subsets of immune system epithelial and neuroendocrine cells. This antigen is expressed by distinct subsets of thymic epithelial and splenic reticular cells and is shared by discrete subsets of anterior pituitary and thyroid neuroendocrine cells. In the thymus, 1D4 expression identified a unique subset of stellate-shaped Ia+ medullary epithelial cells which did not react with thymosin alpha-1 antisera nor with the MoAb A2B5 specific for a GQ ganglioside expressed by thymic hormone-producing cells. The availability of the 1D4 MoAb should facilitate further characterization of 1D4+ immune system epithelial cells and may advance our understanding of neuroendocrine-immune system interactions.

Animals↗