Search PubMed⌕ Search

Biomedical subjects

J D Beck

Publications and source records attributed to J D Beck.

At least 109 records · Page 6Linked to original sources
PubMed1996

Separation of peripheral blood derived stem cells in children.

We performed 28 separations in 10 children from 14 to 44 kg (median: 24 kg) using either the Cobe Spectra or the Fresenius AS 104 cell separator. For children below 20 kg, human albumin solution was used for the last 200 ml of the priming procedure instead of NaCl. Blood flow was reduced to 30 - 50 ml/min depending on the childrens' size and weight to prevent citrate reactions. Within 149 - 337 minutes we processed 3 x the patients' total blood volume and collected 326.9 x 10(6) (76.5-1, 140.0) MNC and 2.03 x 10(6) (0.14-10.12) CD34+ cells per kg body weight. These results were comparable to the results we previously obtained in adults. We conclude from these initial results that PBSC separations with both devices can be adapted successfully to the needs for paediatric patients.

Adolescent↗
PubMed1995

Molecular analysis of the chromosomal breakpoint and fusion transcripts in the acute lymphoblastic SEM cell line with chromosomal translocation t(4;11).

The chromosomal breakpoint and fusion transcripts of the pre-B-leukaemia-derived SEM cell line carrying a reciprocal t(4;11)(q21;q23) translocation were analysed. The breakpoint from derivative chromosome der4 was cloned and sequenced. The crossover site was localized in intron 7 of the ALL-1 gene on chromosome 11q23 and in a large intron of the AF-4 (FEL) gene. RNA transcripts from both wild-type genes and both hybrid genes were detected by reverse transcriptase polymerase chain reaction (RT-PCR) assays. In addition, alternatively spliced mRNA species derived from the der4 chromosome were found. They were generated by using the exon 5' of the breakpoint on der4 as a common splice donor site and the 5' boundaries of exons 8 or 9 of the ALL-1 gene as alternative splice acceptor sites. The hypothesis is proposed that selective pressure operators to maintain the presence of both derivative chromosomes as important elements in the leukaemogenic process.

Base Sequence↗
PubMed1995

A method for adjusting caries increments for reversals due to examiner misclassification.

Two types of reversals occur in longitudinal caries studies, remineralization (true reversals) and reversals due to examiner misclassification (D3 to S; F to S). Since 1966, the standard practice has been to subtract examiner reversals from the crude increment (CCI), resulting in a net caries increment (NCI). The use of the NCI has been based on the assumption that examiners make an equal number of false positive and false negative errors both at baseline and follow-up examination. Consequently, the difference between the two caries prevalence scores would provide an unbiased estimate of caries incidence between examinations. The NCI considers all reversals to be true reversals which is an extreme strategy, particulary when the level of diagnosis is set at lower thresholds. In this study we compromised between the NCI and CCI by creating a simple formula to calculate the caries increment using a prevalence-based adjustment for reversals. The formula is ADJCI = y2(1-(y3/(y3 + y4))), where y2 = S to D or F; y3 = D or F to S; y4 = D to D/F or F to F. The impact of this adjustment is illustrated using data from a random sample of 452 older black and white adults followed over a 3-yr period. The ADJCI was more likely to result in higher caries increments and more observed intergroup differences than the NCI, a finding that has implications for clinical trials. For example, the crude 3-yr coronal DS increment for whites was 0.62, the NCI was 0.26 and the ADJCI was 0.56. There were significant black-white differences for the CCI and ADJCI, but not the NCI. We conclude that the NCI was too severe of an adjustment for reversals for this study population.

Adult↗
PubMed1995

Three-year root caries incidence and risk modeling in older adults in North Carolina.

OBJECTIVES: The purposes of this study were to describe the incidence of root caries and to identify its risk factors in a representative sample of older adults. METHODS: Root caries incidence was estimated and multivariate risk assessment models were developed to identify predictors for root caries in a three-year follow-up study of 234 black and 218 white noninstitutionalized adults aged 65 and older residing in North Carolina. RESULTS: During the observation period, 29 percent of blacks developed root caries, compared to 39 percent of whites (P < .05). The mean net DFS increment per person was 0.55 +/- 0.13 root surfaces for blacks vs 0.80 +/- 0.21 for whites (P > .32). Multivariate logistic regression analysis indicated that blacks wearing a partial denture, having some root fragments, having an average gingival recession > or = 2 mm, and being free of P. intermedia were at greater risk for developing new root caries. The model for whites showed that retired people with their most severe gingival recession > or = 4 mm, an average probing pocket depth > or = 2 mm, and taking antihistamines were more likely to develop new lesions. CONCLUSIONS: These findings suggest that older blacks had less risk of root caries than whites, and in both groups indicators of poor periodontal status increased the risk of root caries.

Aged↗
PubMed1995

Eighteen-month incidence of tooth loss among older adults in North Carolina.

This study investigated tooth loss in North Carolina adults 65 years of age or older. A random sample of 335 Blacks and 284 Whites participated in dental examinations and interviews at baseline and again after 18 months. Blacks were more likely than Whites to lose at least one tooth (36% vs 19%), and they lost more teeth on average (1.0 vs 0.4). Several oral disease conditions and symptoms were related to tooth loss, but many other hypothesized factors were not. Risk models were inconclusive in the identification of factors related to risk of tooth loss.

Aged↗
PubMed1994

Characteristics of older adults experiencing periodontal attachment loss as gingival recession or probing depth.

While attachment loss currently is the best field examination indicator that periodontal disease has progressed, this measure is not disaggregated enough to differentiate between attachment loss that results in deeper pockets and attachment loss that results primarily in recession of the gingiva. If these two conditions have different etiologies, then efforts at predicting who will experience the condition from a single, general risk assessment model will be difficult. The purpose of this paper is to determine whether the characteristics of people who experience attachment loss primarily as increased probing depths are different from those people who experience attachment loss primarily as gingival recession. Baseline and 18-month follow-up periodontal measures were gathered on a representative sample of community-dwelling adults aged 65+. Based on measurement errors obtained one week apart on a reliability subsample, a threshold level of 3+mm was set to define attachment loss. Attachment loss was further characterized as resulting from mostly increased probing depth or from mostly increased gingival recession. In mesio-buccal sites, 58% of the people had attachment loss mostly due to increased probing depth with 42% having attachment loss mostly due to gingival recession. For buccal sites, the figures were 24% and 76% respectively. The logistic regression models for both sites indicated that people who had their attachment loss in the form of increased probing depths had different characteristics than people who had most of their attachment loss in the form of gingival recession.(ABSTRACT TRUNCATED AT 250 WORDS)

Black or African American↗
PubMed1994

Eighteen-month coronal caries incidence in North Carolina older adults.

In this longitudinal study of a random sample of North Carolinians over the age of 65 and living in their homes, 325 blacks and 280 whites were examined and interviewed 18 months after baseline examinations. Coronal caries incidence was greater among whites than blacks. The increment due to teeth becoming root fragments were similar for both races; however, there were more newly crowned teeth among whites. Newly crowned surfaces were not used as part of the caries increment in logistic regression models to investigate potential risk predictors. For blacks, caries development over the 18-month period was associated with a higher lactobacillus score and more coronal caries at baseline, more previously filled coronal surfaces, and lack of active membership in clubs or other groups. For whites, having no self-reported tooth sensitivity, having a lower socioeconomic index score, taking antihistamine medications at baseline, and having the perception of more problems after the age of 40 than before were all associated with the development of coronal caries.

Black or African American↗
PubMed1994

Incidence of attachment loss in community-dwelling older adults.

Since 1985, only four studies have been published that present data on attachment loss in populations. The purpose of this study was to present the incidence of attachment loss over an 18-month period in a representative sample of community-dwelling older adults. In addition, the utility of multivariate prediction models to distinguish between people who will and will not experience disease progression was explored. The Piedmont 65+ Dental Study of the Elderly is a longitudinal investigation of a random sub-sample of over 1,000 community-dwelling people over the age of 65 in five contiguous North Carolina counties. The five dentists who conducted the in-home examinations and interviews at baseline also participated at 18 months and examined the same subjects. The overall attrition rate for blacks was 27% and the rate for whites was 23%. At 18-months, the baseline attachment level scores for those subjects who were lost from the study were not significantly different from the scores of those who remained in the study. A change in attachment loss of 3 mm or more over the 18 months was set as a conservative estimate of actual change taking place. Blacks were significantly more likely to experience attachment loss irrespective of the number of sites involved (P < .05). Approximately half the people had at least one losing site and about one-third of the blacks and one-fourth of the whites had at least two losing sites. A total of 24% of blacks and 16% of whites had 3 or more losing sites.(ABSTRACT TRUNCATED AT 250 WORDS)

Black or African American↗
PubMed1994

Methods of assessing risk for periodontitis and developing multifactorial models.

In assessing risk for disease, periodontitis can be thought to be more like some of our common medical conditions: certain people are at higher risk than others, and efforts at prevention and intervention involve a combination of personal behaviors and professional practices. This paper presents some principles of designing risk assessment studies. In addition, the choices that must be made in deciding what is high risk and the type of model to be constructed are presented along with implications of each alternative. Terms such as risk indicators, risk factors, risk predictors, risk models, and prediction models are presented and discussed. To illustrate some of the issues, findings from the Piedmont 65+ Dental Study (a longitudinal study of oral health in older adults) indicate that: 1) indicators of risk developed from cross-sectional studies quite often are not confirmed as risk factors in longitudinal studies and longitudinal data implicate additional factors; 2) oral risk factors were important in explaining disease progression, but other categories of risk factors also played an explanatory role; 3) the risk models were able to predict who would experience attachment loss at some time during the 3-year period with a high degree of accuracy, but there was only moderate success at predicting who would not experience attachment loss; 4) including risk predictors in the models did improve the ability of one model to predict attachment loss, but the risk predictor masked the presence of an important risk factor; and 5) it is highly likely that adding measures of host defense mechanism to the study could result in improved models.

Aged↗
PubMed1994

Attachment loss trends over 3 years in community-dwelling older adults.

Most of our knowledge regarding the natural history of periodontitis in adults has come from clinical studies of dental patients. However, it is known that dental patients usually are not representative of what actually happens in the population. For this type of information, epidemiologic studies are required. The purpose of this paper is to present the trends in attachment loss over a 3-year period in a population of community-dwelling elderly blacks and whites. Specifically, this paper presents attachment loss trends both at the person and site level to address the following issues: 1) whether attachment loss during one period in time makes a person at higher risk for attachment loss at a subsequent period; 2) whether sites with deeper periodontal pockets at baseline are more likely to experience future attachment loss; and 3) whether teeth that experience attachment loss during one time period are more likely to be lost at the next time period. In 1988, the University of North Carolina School of Dentistry initiated the Piedmont 65+ Dental Study, which is a subsample of the parent study, the Piedmont 65+ Study of the Elderly under the direction of investigators from Duke University. The dental study subsample was designed to elicit 800 dentate respondents in the 5-county area who were examined again at 18 and 36 months. Our findings indicated that, for the two 18-month periods investigated, attachment loss during the first period was related positively to the incidence of attachment loss at a subsequent period at the person level, but not at the site level.(ABSTRACT TRUNCATED AT 250 WORDS)

Black or African American↗
PubMed1993

The oral status of elderly removable partial denture wearers.

A random sample of 1019 elderly home dwelling persons participated in this study. There were 809 dentate respondents, 28.6% of whom wore removable partial dentures. They were examined for coronal and root caries, gingival recession, pocket depth and loss of gingival attachment. The removable partial dentures were also evaluated. Abutment teeth were found to be more likely to have caries and periodontal disease than all other teeth. Using a MANOVA statistical procedure, the analysis indicated that the partial denture itself, irrespective of any professionally determined problems with the denture, appears to affect coronal and root caries on the teeth of partial denture wearers. Partial dentures judged to need repair or adjustment were related to periodontal status. The data on adverse effects of partial dentures suggest a need for patient education by the dentist and through public health measures, and good oral self care and regular professional recall for people who wear removable partial dentures.

Black or African American↗
PubMed1993

The epidemiology of root surface caries: North American studies.

After some problems resulting from the lack of standardized methods in the conduct of root caries studies and the lack of standardized reports of findings are reviewed, the prevalence and incidence of root surface caries in North America are reviewed through a combination of epidemiologic studies and large clinical trials. As part of this review, the available evidence on the relationship between root caries and missing teeth is presented. These data lead to the conclusion that the prevalence and, to some extent, the incidence of root caries are underestimated in adults with missing teeth. This review resulted in a number of observations regarding the status of root caries as an oral health problem. First, there is little evidence that would allow conclusions regarding the secular increase or decrease in the prevalence or incidence of root caries to be drawn. Other observations gleaned include the remarkably similar prevalence and incidence rates obtained from the studies reviewed, positive associations between root caries and age, negative associations between the prevalence and incidence of root caries and consumption of water containing fluoride, indications that root caries is a problem in adults with incidence rates that approach caries rates in children, and associations between the prevalence and incidence of root caries and a wide variety of oral, behavioral, and medical conditions. The final observation is the need for the acceptance of conventions for the definition of root caries as well as the reporting of findings in order for more firm conclusions to be drawn from future studies.

Adult↗
PubMed1993

The distribution and interrelationship of Actinobacillus actinomycetemcomitans, Porphyromonas gingivalis, Prevotella intermedia, and BANA scores among older adults.

In a random sample of subgingival dental plaque samples from 375 blacks and 300 whites aged 65 and older, immunofluorescence assays for 3 target pathogens including Actinobacillus actinomycetemcomitans, Porphyromonas gingivalis, and Prevotella intermedia, and BANA enzyme analysis were carried out. Blacks had significantly greater proportions of P. gingivalis and P. intermedia in their subgingival plaque and had significantly higher BANA scores. These assay results were investigated for concordance with each other and with 2 cariogenic salivary bacteria, Streptococcus mutans and lactobacilli. In general for both races, the periodontal pathogens were more likely to occur in combination with each other than with either S. mutans or lactobacilli. P. gingivalis and P. intermedia were more frequently associated with each other than with A. actinomycetemcomitans. There was a significant negative concordance between BANA and A. actinomycetemcomitans in whites and a significant positive concordance between BANA and P. intermedia in blacks.

Black or African American↗
PubMed1993

[Medulloblastomas--the results after postoperative radiotherapy with and without adjuvant chemotherapy].

Between 1975 and 1991, 40 patients with newly diagnosed medulloblastoma were treated at the authors' institutions. After aggressive surgical resection 39/40 (98%) received craniospinal radiation therapy with a local boost to the posterior fossa and other macroscopically involved areas. A group of 29 patients was treated with adjuvant chemotherapy. The five-year actuarial survival and event-free survival were 75% and 65%, respectively. Survival was significantly better for patients treated after 1981 as compared to those treated between 1975 and 1980 (p = .02). Younger age (two to four years) was associated with a better prognosis (p = .02). The extend of resection, Chang-stage, radiation dose to posterior fossa and the use of chemotherapy did not significantly impact on survival and relapse-free survival.

Actuarial Analysis↗