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Biomedical subjects

K M Thompson

Publications and source records attributed to K M Thompson.

At least 37 records · Page 2Linked to original sources

Sexual victimization and adolescent weight regulation practices: a test across three community based samples.

OBJECTIVE: This study had four objectives: 1) to examine the association between sexual victimization and weight regulation across three samples of adolescent girls, 2) to assess whether sexual victimization is associated with more extreme forms of weight regulation in girls, 3) to discern whether sexual victimization has implications for the use of multiple forms of weight regulation, and 4) to address the role of physical victimization in explaining these relationships. METHOD: Data from three separate samples of 9th-12th graders were used to test these hypotheses. Girls from the upper Midwest responded to survey questions related to victimization and weight regulation in a largely urban sample (N = 2,086), a rural sample (N = 2,629), and a statewide sample (N = 966). RESULTS: Logistic regression revealed that sexual victimization was consistently associated with weight regulation in adolescent girls, independent of the effects of physical victimization. In the urban sample, being sexually victimized was associated with an increase in the probability of purging by 18% relative to not being sexually victimized. Sexual victimization was associated more strongly with extreme forms of weight regulation and significantly discriminated whether girls would choose multiple weight regulation forms. CONCLUSIONS: Sexual victimization contributes unique variance to the probability that girls will practice weight regulation techniques. Data from three independent samples confirms that being violated sexually places girls at risk for various health compromising eating behaviors.

Adolescent↗

An assessment of the recidivism rates of substantiated and unsubstantiated maltreatment cases.

OBJECTIVE: This study assembles information about the large number of maltreatment reports that are determined by social services to be unsubstantiated. Specifically, we assess whether the status of a maltreatment case (substantiated vs. unsubstantiated) has implications for recidivism. Recidivism rates for substantiated and unsubstantiated maltreated juveniles were also compared to juvenile offenders. METHOD: Juvenile court records for 15,812 juveniles were assessed over a 3 year period. The data included 2558 maltreatment cases. Fifty-four percent of these cases were unsubstantiated. Logistic regression analysis was employed to assess the probability of recidivism based on time one referral status. RESULTS: Youth whose maltreatment allegations were unsubstantiated had significantly lower odds of recidivating than abused youth. Having a case recorded as unsubstantiated lowered a youth's odds of subsequent offending by 55% relative to being abused. The probability of recidivating was highest for juvenile offenders, followed in order by maltreated youth and youth whose reports were unsubstantiated. DISCUSSION: This is one of the first studies to examine the court histories of substantiated and unsubstantiated maltreatment cases. If the subsequent outcomes following maltreatment investigations are used as an indicator of seriousness, our results suggest that assessment caseworkers are successfully sorting out the serious from the less serious cases.

Child↗

A dynamic programming approach to the efficient design of clinical trials.

If the prospective evaluation of all feasible strategies of patient management is not possible or efficient then this poses a number of questions: (i) which clinical decision problems will be worth evaluating through prospective clinical research; (ii) if a clinical decision problem is worth evaluating which of the many competing alternatives should be considered "relevant" and be compared in the evaluation; (iii) what is the optimal (technically efficient) scale of this prospective research; (iv) what is an optimal allocation of trial entrants between the competing alternatives; and (v) what is the value of this proposed research? The purpose of this paper is to present a Bayesian decision theoretic approach to the value of information which can provide answers to each of these questions. An analysis of the value of sample information was combined with dynamic programming and applied to numerical examples of sequential decision problems. The analysis demonstrates that this approach can be used to establish: optimal sample size; optimal sample allocation; and the societal payoff to proposed research. This approach provides a consistent way to identify which of the competing alternatives can be regarded as "relevant" and should be included in any evaluative study design. Bayesian decision theory can provide a general methodological framework that can ensure consistency in decision making between service provision, research and development, and the design, conduct and interpretation clinical research.

Bayes Theorem↗

Significantly depressed percentage of CD27+ (memory) B cells among peripheral blood B cells in patients with primary Sjögren's syndrome.

CD27 has been found to be expressed on somatically mutated B cells and is thus a positive marker for memory B cells in peripheral blood (PB). Since abnormal immunogloblin (Ig) production is characteristic of the autoimmune diseases primary Sjögren's syndrome (pSS) and rheumatoid arthritis (RA), we have analyzed in detail the CD27 expression on PB B cell from these patient groups. Staining of PB B cells with monoclonal antibodies (MoAb) specific for CD19 and CD27 revealed a significantly depressed percentage of CD27+ PB B cells in patients with pSS (14.8 +/- 1.6%) compared to both healthy donors (31.3 +/- 4.7%, P = 0.005) and patients with RA (40.8 +/- 4.1%, P = 0.0001). In addition, the percentages of both the IgD+CD27+ and the IgD-CD27+ B-cell subpopulations were significantly lower in pSS patients compared to RA patients and healthy donors. However, the relative proportion of IgD- and IgD+ cells among the CD27+B cells were almost the same for the three groups. Our data suggest a disturbance in the differentiation of peripheral B cells and possibly a bias towards plasma cell differentiation, resulting in a depressed percentage of CD27+ memory PB B cells in pSS. These results are potentially of pathological significance and of diagnostic value.

Adult↗

T-cell responses to viral, bacterial and protozoan antigens in rheumatoid inflammation. Selective migration of T cells to synovial tissue.

OBJECTIVE: To identify any preferential or selective migration of T-cell specificities to inflamed tissues of rheumatoid arthritis (RA) patients. METHODS: Lymphocytes from peripheral blood (PB) and synovial tissue (ST) were isolated from RA patients and stimulated with a panel of crude antigen preparations from 18 bacterial, protozoan and viral sources. Proliferative responses of the T lymphocytes to each antigen and group of antigens were compared in PB and ST. Antigen-specific T-cell clones were developed and their migratory capacities towards synovial chemokines were compared. RESULTS: ST-derived T cells showed a small but significantly higher stimulation index (SI) to the group of intestinal bacteria compared with PB T cells. Conversely, responses of ST-derived T cells to Acanthamoeba polyphaga (AP) were both profoundly and significantly lower compared with PB-derived T cells. The viral antigens as a whole gave comparable reactivities in blood and ST. The migratory capacity of AP-specific T-cell clones towards chemokines produced by ST was profoundly poorer compared with Campylobacter jejuni- and herpes simplex virus-specific T-cell clones. CONCLUSIONS: The results indicate a selective migration of T cells of given specificities to the inflamed rheumatoid synovium.

Acanthamoeba↗

Proposed occupational exposure limits for select ethylene glycol ethers using PBPK models and Monte Carlo simulations.

Methoxyethanol (ethylene glycol monomethyl ether, EGME), ethoxyethanol (ethylene glycol monoethyl ether, EGEE), and ethoxyethyl acetate (ethylene glycol monoethyl ether acetate, EGEEA) are all developmental toxicants in laboratory animals. Due to the imprecise nature of the exposure data in epidemiology studies of these chemicals, we relied on human and animal pharmacokinetic data, as well as animal toxicity data, to derive 3 occupational exposure limits (OELs). Physiologically based pharmacokinetic (PBPK) models for EGME, EGEE, and EGEEA in pregnant rats and humans have been developed (M. L. Gargas et al., 2000, Toxicol. Appl. Pharmacol. 165, 53-62; M. L. Gargas et al., 2000, Toxicol. Appl. Pharmacol. 165, 63-73). These models were used to calculate estimated human-equivalent no adverse effect levels (NAELs), based upon internal concentrations in rats exposed to no observed effect levels (NOELs) for developmental toxicity. Estimated NAEL values of 25 ppm for EGEEA and EGEE and 12 ppm for EGME were derived using average values for physiological, thermodynamic, and metabolic parameters in the PBPK model. The uncertainties in the point estimates for the NOELs and NAELs were estimated from the distribution of internal dose estimates obtained by varying key parameter values over expected ranges and probability distributions. Key parameters were identified through sensitivity analysis. Distributions of the values of these parameters were sampled using Monte Carlo techniques and appropriate dose metrics calculated for 1600 parameter sets. The 95th percentile values were used to calculate interindividual pharmacokinetic uncertainty factors (UFs) to account for variability among humans (UF(h,pk)). These values of 1.8 for EGEEA/EGEE and 1.7 for EGME are less than the default value of 3 for this area of uncertainty. The estimated human equivalent NAELs were divided by UF(h,pk) and the default UFs for pharmacodynamic variability among animals and among humans to calculate the proposed OELs. This methodology indicates that OELs (8-h time-weighted average) that should protect workers from the most sensitive adverse effects of these chemicals are 2 ppm EGEEA and EGEE (11 mg/m(3) EGEEA, 7 mg/m(3) EGEE) and 0.9 ppm (3 mg/m(3)) EGME. These recommendations assume that dermal exposure will be minimal or nonexistent.

Administration, Inhalation↗

Estimation of tuberculosis risk and incidence under upper room ultraviolet germicidal irradiation in a waiting room in a hypothetical scenario.

Environmental control measures (ventilation, high-efficiency particulate air filtration, and upper room ultraviolet germicidal irradiation [UVGI]) are recommended to effectively control tuberculosis (TB) transmission from unsuspected TB patients in high-risk settings, but the effectiveness of their use is not often clear. This study presents a simulation model for a hypothetical hospital waiting room, in which the number of susceptible immunocompetent people in the waiting room follows a Poisson distribution (M = 5) in either low (annual number of TB patients = 5) or high TB risk settings (annual number of TB patients = 50), and used the model to evaluate the reduction of TB transmission risk by upper room UVGI. An exponential dose-response model was used for TB transmission and a two-zone model was used for evaluating the effect of upper room UVGI. Upper room UVGI reduced TB risk by 1.6-fold at 3 microW/cm2 UV irradiance in the upper room in the low TB risk setting and by 4.1-fold at 15 microW/cm2 UV irradiance in the upper room in the high TB risk setting. Use of upper room UVGI also reduced the mean annual new infection rate from 2.2 to 1.3 infections per year at 3 microW/cm2 and to 0.6 infections per year at 15 microW/cm2 in our hypothetical high-risk settings. The effect of upper room UVGI was sensitive to both vertical air velocity (air mixing) and UV irradiance level. Results from partitioning variability indicate that most variability of TB transmission risk came from waiting time in our hypothetical hospital.

Computer Simulation↗

The risk of groundling fatalities from unintentional airplane crashes.

The crashes of four hijacked commercial planes on September 11, 2001, and the repeated televised images of the consequent collapse of the World Trade Center and one side of the Pentagon will inevitably change people's perceptions of the mortality risks to people on the ground from crashing airplanes. Goldstein and colleagues were the first to quantify the risk for Americans of being killed on the ground from a crashing airplane for unintentional events, providing average point estimates of 6 in a hundred million for annual risk and 4.2 in a million for lifetime risk. They noted that the lifetime risk result exceeded the commonly used risk management threshold of 1 in a million, and suggested that the risk to "groundlings" could be a useful risk communication tool because (a) it is a man-made risk (b) arising from economic activities (c) from which the victims derive no benefit and (d) exposure to which the victims cannot control. Their results have been used in risk communication. This analysis provides updated estimates of groundling fatality risks from unintentional crashes using more recent data and a geographical information system approach to modeling the population around airports. The results suggest that the average annual risk is now 1.2 in a hundred million and the lifetime risk is now 9 in ten million (below the risk management threshold). Analysis of the variability and uncertainty of this estimate, however, suggests that the exposure to groundling fatality risk varies by about a factor of approximately 100 in the spatial dimension of distance to an airport, with the risk declining rapidly outside the first 2 miles around an airport. We believe that the risk to groundlings from crashing airplanes is more useful in the context of risk communication when information about variability and uncertainty in the risk estimates is characterized, but we suspect that recent events will alter its utility in risk communication.

Accidents, Aviation↗

An observational study of object mouthing behavior by young children.

OBJECTIVE: Mouthing behavior in infants and young children <3 years old is a poorly quantified yet normal part of early childhood development. Increasingly, safety and risk assessments involving materials that may be mouthed depend on accurate estimates of oral contact time. This study reports the results of an observational study performed to investigate and obtain data on mouthing behavior of objects for children up to 3 years old. METHODOLOGY: The study used a standard diary form with instructions for participating parents to observe their child in a normal environment (primarily home), and to document both the type and duration of each item mouthed. Phase I (pilot) consisted of 30 children each observed for 1 day, divided equally between the ages of 0 to 18 months (n = 15) and 19 to 36 months (n = 15), whereas Phase II included more participants (n = 92 aged 0-18 months; n = 95 aged 19-36 months). Phase III included observations for 5 nonconsecutive days over a 2-month period on 168 children between the ages of 3 to 18 months (at study initiation), and focused on total mouthing time of objects, exclusive of pacifiers. RESULTS: The data collected during the first 2 phases were pooled and analyzed together. For all participants between the ages of 0 and 18 months (n = 107), the average daily duration of mouthing objects included: pacifiers (108 minutes), plastic toys (17 minutes), teethers (6 minutes), and other objects (9 minutes). The results for children 19 to 36 months old (n = 110) included: pacifiers (126 minutes), plastic toys (2 minutes), teethers (0 minutes), and other objects (2 minutes). Although no significant difference existed between the 2 age ranges for pacifier mouthing duration, a statistically significant difference was observed for nonpacifier objects. For Phase III, the average daily mouthing time for all objects (excluding pacifiers), based on 5 nonconsecutive days of observation for 168 children, was 36 minutes (n = 793 valid child observation days). CONCLUSIONS: Results of this study indicate that mouthing behavior is dependent on age and the types of items that are mouthed. Duration of mouthing varies among children, with some consistently not mouthing any objects and with a very small number mouthing objects for >2 hours a day. The study also revealed wide variability in the types of objects mouthed, including many nontoy objects. Children mouth pacifiers significantly longer than other objects, regardless of age. Significantly increased mouthing time of all nonpacifier objects is reported for children in the 0- to 18-month range compared with the 19- to 36-month range.

Algorithms↗

Depiction of alcohol, tobacco, and other substances in G-rated animated feature films.

OBJECTIVE: To quantify and characterize the depiction of alcohol, tobacco, and other substances in G-rated animated feature films. METHOD: The content of all G-rated animated feature films released in theaters between 1937 and 2000, recorded in English, and available on videocassette in the United States by October 31, 2000, was reviewed for portrayals of alcohol, tobacco, and other substances and their use. Duration of scenes depicting alcohol, tobacco, or other substances; type of characters using them (good, neutral, or bad); and correlation of amount and type used with character type and movie type were evaluated. RESULTS: Of the 81 films reviewed, 38 films (47%) showed alcohol use (mean exposure: 42 seconds per film; range: 2 seconds to 2.9 minutes) and 35 films (43%) showed tobacco use (mean exposure: 2.1 minutes per film; range: 2 seconds to 10.5 minutes). Analysis of time trends showed a significant decrease in both tobacco and alcohol use over time (both corrected for total screen duration and uncorrected.) No films showed the use of illicit drugs, although 3 films showed characters consuming a substance that transfigured them and 2 films showed characters injected with a drug. Analysis of the correlation of alcohol and tobacco depiction revealed several scenes in which alcohol and tobacco were shown in use in the same scene and that bar scenes in these movies depict a significant amount of drinking, smoking, and violence. Three films contained a message that a character should stop smoking but none contained messages about restricting consumption of alcohol. CONCLUSIONS: The depiction of alcohol and tobacco use in G-rated animated films seems to be decreasing over time. Nonetheless, parents should be aware that nearly half of the G-rated animated feature films available on videocassette show alcohol and tobacco use as normative behavior and do not convey the long-term consequences of this use.

Alcohol Drinking↗

Complexities of measuring antagonist potency at P2X(7) receptor orthologs.

The ability of P2 antagonists to affect agonist-stimulated fluorescent dye accumulation in cells expressing human, rat, or mouse P2X(7) receptors was examined. Several compounds, including pyridoxalphosphate-6-azophenyl-2',4'-disulfonic acid (PPADS), which was previously thought to be a weak P2X(7) receptor antagonist, possessed high potency (nanomolar IC(50)) at human and rat P2X(7) receptors. However, there were species differences in antagonist potency with PPADS, pyridoxal 5'-phosphate (P5P), and periodate-oxidized ATP (OxATP) exhibiting 20- to 500-fold higher potency for human than for mouse P2X(7) receptors. HMA (5-(N,N-hexamethylene)amiloride) was also selective for human over rat P2X(7) receptors but potentiated responses at mouse P2X(7) receptors. Coomassie Brilliant Blue G (CBB) was a nonselective antagonist with high potency at mouse P2X(7) receptors (IC(50) approximately 100 nM). All compounds were noncompetitive antagonists, and potency could only be quantified by measuring IC(50) values. These values were similar when determined against EC(50) concentrations of ATP or 2'- and 3'-O-4(-benzoylbenzoyl)-ATP and, for most compounds, only slightly (3- to 5-fold) affected by agonist concentration. However, IC(50) values for KN62 (1-[N,O-bis(5-isoquinolinesulfonyl)-N-methyl-L-tyrosyl]-4-phenylpiperazine) and suramin, varied up to 25-fold depending upon agonist concentration. Furthermore, IC(50) values for KN62 and OxATP were 10-fold lower at 22 degrees C than at 37 degrees C, whereas IC(50) values for PPADS, P5P, suramin, and OxATP were up to 20-fold lower in NaCl than in sucrose buffer. Potency estimates for CBB and PPADS decreased 5-fold in the presence of bovine serum albumin, possibly due to protein binding. Given the species differences, and the effects of assay conditions on antagonist potency, caution must be exercised when interpreting results obtained with the available antagonists.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗

Marijuana use among adolescents: trends, patterns, and influences.

This article reviews current marijuana conditions, trends, and influences among adolescents. Data show that prevalence rates vary markedly among youth, showing higher usage rates in the United States and Western Europe and lower rates among Mediterranean and Scandinavian youth. Urianalysis studies show that American juvenile arrestees are testing positive for cannabis at increasing rates. Influences that are central to marijuana use include being older, being male, experiencing family conflict, having peer models for use, and suffering from mood and anxiety disorders. More information is needed on how much gene-based evolutionary traits are relevant to marijuana abuse. Criticisms of school-based drug education programs have lead to the emergence of more comprehensive and enduring prevention programs. Concern about rising levels of marijuana abuse, lack of accountability, and dual diagnoses have given rise to juvenile drug courts. Preliminary reports suggest that these two strategies could show promise in reducing marijuana use and abuse, although rising THC yields could counteract these efforts.

Adolescent↗

Analysis of 'natural' and vaccine-induced haemophilus influenzae type B capsular polysaccharide serum antibodies for 3H1, a V3-23-associated idiotope.

The variable (V-) region repertoire of antibodies (Abs) to Haemophilus influenzae capsular polysaccharide (Hib PS) has been extensively studied in individuals vaccinated against the microbe, but to a lesser extent in subjects who generated such Abs in response to a 'natural' encounter with this microbe or its antigenic mimics. To gain an insight into the repertoire of Hib PS-reactive Abs in vaccinated and non-vaccinated individuals, we used a monoclonal Ab, 3H1, which detects an idiotypic marker associated with an Ab V-region gene, V3-23. We show here that Hib PS-reactive Abs with detectable 3H1 idiotope can be quantified by an indirect inimunoezymatic assay in serum samples of non-vaccinated healthy adults as well as of recently vaccinated healthy infants. The percentage of Abs that was simultaneously Hib PS-reactive and 3H1-positive ranged widely (from 0 to 68%) among individual serum samples from both groups of subjects. No dramatic differences in the expression of 3H1 idiotope on Hib PS-reactive Abs were found between vaccinated and non-vaccinated individuals. Our results are consistent with the hypothesis that the utilization of V-region genes in Hib PS-reactive Abs that individuals generate after a 'natural' encounter with Hib PS or its mimics is similar to that in these Abs elicited by Hib PS conjugate vaccines.

Adult↗

Smoking and weight control in adolescent females.

This paper examines the association between smoking and various weight control techniques among adolescent girls in two school-based samples. Previous studies have relied heavily on clinical trials of adults and have focused mainly on dietary restraint rather than purging behavior. This study seeks to determine whether purging is associated with smoking and if purging and dietary restraint effects upon smoking are additive or synergistic. Data from adolescent girls were gathered from two school-based surveys conducted in the upper Midwest. Assessments were conducted for smoking, dietary restraint, diet pill use, and purging. Logistic regression was used to test for main and interaction effects. Analysis revealed significant associations between smoking and weight control. Purging was more highly associated with smoking than dietary restraint or diet pill use. The form of these associations was interactive rather than additive in both data sets. Nonpurging girls were significantly more likely to smoke if they were dieting or using diet pills than if they were not practicing dieting behavior. Thus, the effect of dieting and diet pill use on smoking is dependent on purging behavior. Weight control is associated with smoking behavior in adolescent girls but the form of these associations may be more complex than originally thought. Future research is needed to determine if there are two subtypes of smoking-weight control girls.

Journal Article↗

Molecular analysis of human immunoglobulin heavy chain variable region associated determinants recognized by anti-VH3 antibodies 7B4, B6 and D12.

7B4, B6 and D12 are murine monoclonal antibodies (MoAb) that bind to some human immunoglobulin heavy chain products of the closely related V3-30, V3-30.3 and V3-33 genes from the VH3 family. B6 and D12 have additional reactivities with some immunoglobulins (Ig) encoded by the V3-11 and V3-7 genes; D12 also reacts with some V3-43 gene Ig. We show here, by site-directed mutagensis, that the lysine at position 57 in the complementarity-determining region 2 (CDR-2) of the V3-30 gene product is crucial for epitope recognition by all three anti-VH3 MoAbs. Further analysis of the amino-acid sequences of a large panel of Ig reactive, or nonreactive, with MoAb 7B4 indicates that the determinant recognized by 7B4 is dependent on the presence of the tetrapeptide sequence NKYY between positions 56 and 59 in the CDR-2. Comparing the efficiency of 7B4 reactivity with VH3 gene-encoded human Ig indicates that amino-acid position 4 in the frame region 1 (FR-1) may also influence the binding of 7B4 to Ig encoded by three very closely related germline genes, V3-30, V3-30.3 and V3-33. NKYY is also found on the gp120 V3 region of human immunodeficiency virus (HIV)-2, SIV and HTLV-4. We also report that other tetrapeptide sequences found on the 56-59 motif of heavy chain variable regions encoded by germline genes are expressed on the solvent exposed V2 region of gp120 of HIV-1 isolates. The possible significance of these observations is discussed.

Amino Acid Sequence↗

Exposure efficiency: concept and application to perchloroethylene exposure from dry cleaners.

Standard approaches for computing population exposures due to specific sources of air pollutants are relatively complex. In many cases, more simple and approximate methods would be useful. This paper develops an approach, based on the concept of exposure efficiency, that may be used for estimating the impact of a source (or source class) on the integrated population exposure. The approach is illustrated by an example, which uses the concept of exposure efficiency to examine the impact of perchloroethylene emissions from dry cleaners in the United States. The paper explores the geographic variability of exposure efficiency by evaluating it for each of 100 randomly selected dry cleaners. For perchloroethylene, which has a long atmospheric residence time, the site-to-site variability in exposure efficiency is found to be relatively small. This suggests that simple exposure assessments, based on generic distributional characterizations of exposure efficiency, may be used in risk assessments without introducing appreciable uncertainty. For many compounds, like perchloroethylene, the uncertainty inherent in the estimation of cancer potency or source emissions would dominate these small errors.

Carcinogens↗

Relationship of childhood sexual abuse and eating disturbance in children.

OBJECTIVE: To test the hypothesis that childhood sexual abuse increases the risk of eating disturbance in children. METHOD: Data obtained from 20 sexually abused children were compared with data obtained from 20 nonabused control children. All subjects were female and between the ages of 10 and 15 years. Subjects completed a battery of tests assessing eating disorder behaviors, body image concern, and childhood trauma history. RESULTS: Comparison of the 2 groups revealed that the abused children had higher levels of weight dissatisfaction and purging and dieting behavior. Furthermore, abused children reported eating less than control children when they felt emotionally upset. Abused children were less likely than control children to exhibit perfectionistic tendencies, but more likely to desire thinner body types. CONCLUSIONS: This is the first controlled study to examine the relationship between childhood sexual abuse and eating disturbance which relied on children as subjects. The results support previous findings with adult subjects which indicate that a history of childhood sexual abuse is associated with weight and body dissatisfaction, along with purging and dietary restriction.

Adolescent↗