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Biomedical subjects

L J Brown

Publications and source records attributed to L J Brown.

At least 55 records · Page 3Linked to original sources
PubMed1998

Differences in net incomes of male and female owner general practitioners.

The authors analyzed the mean net income of a cohort of male and female dentists with similar demographics and practice characteristics. The authors found that the average net income of these male dentists is higher than it is for their female counterparts. This difference is statistically significant and monetarily tangible, amounting to an annual net income balance of about $26,000 (22 percent) in favor of male dentists. If such a difference in net income persists, it could affect the profession as well as the distribution of dental school enrollments.

Adult↗
PubMed1998

Work force trends that influence dental service capacity.

Although the total number of active private dentists increased by 21.7 percent between 1982 and 1995, the number of active private part-time dentists increased by 104 percent, while the number of active private full-time dentists increased by 8 percent. Thus, the total number of hours active private dentists spent in the office has not increased to the same extent as the number of active private dentists. During the same period, however, the average number of hours spent treating patients increased, indicating that dentists are becoming more efficient in directing their office hours toward clinical dentistry. The distribution of active private part-and full-time dentists and the actual number of hours they spent in the dental office and spent treating patients provide a more complete picture of the capacity of the dental care delivery system than only looking at the increase in the total number of dentists.

Dental Care↗
PubMed1998

Net income, gross billings and practice expenses of independent dentists.

One way to measure the vitality of a profession is to look at the trend in its practitioners' real incomes. During the 10-year period 1986 through 1995, the average real net income of all independent dentists rose 30.7 percent, or 2.7 percent annually, after being adjusted for inflation using 1995 U.S. dollars. The national per capita personal income (base = 1995) increased 10.1 percent during this same period, or about 1.0 percent annually [corrected]. Using real per capita income as a benchmark, the authors found that the purchasing power of dentists as a group has increased more rapidly than the purchasing power of the overall U.S. population.

Fees, Dental↗
PubMed1998

Solo general practitioners and specialists.

A solo practitioner is the sole owner of and the only dentist in a dental practice and also is the most common type of dental practitioner in the United States. The authors provide a brief look at solo general practitioners' and specialists' characteristics, including employment status, number of employees, time spent in the office, number of patient visits per week, gross billings, net income and practice expenses.

Accounting↗
PubMed1998

Dental procedure fees 1975 through 1995: how much have they changed?

A shift toward diagnostic and preventive dentistry in the last two decades is evident from the change in the number of dental procedures performed, as well as the change in the percentage of time spent performing different types of procedures. During the period 1975 through 1995, the average nominal fees for selected dental procedures increased. Once inflation was taken into account, however, the increase in the average real fees charged was more modest.

Adult↗
PubMed1998

Periodontal diseases in the United States population.

Recent epidemiologic surveys and studies have provided important information on the prevalence, extent, and severity of periodontal diseases in the United States. Over 50% of adults had gingivitis on an average of 3 to 4 teeth. Subgingival calculus was present in 67% of the population. Adult periodontitis, measured by the presence of periodontal pockets > or = 4 mm, was found in about 30% of the population on an average of 3 to 4 teeth. Severe pockets > or = 6 mm were found in less than 5% of the population. Attachment loss > or = 3 mm was found in 40% of the population. Gingival recession accounted for a significant amount of attachment loss. The prevalence of early-onset periodontitis ranged from less than 1% in 14- to 17-year-olds to 3.6% in young adults aged 18 to 34. Extensive and severe periodontitis was much more prevalent in minorities, people with less than a high school education, and those who had seen a dentist infrequently and had subgingival calculus. Smoking and diabetes have been identified as risk factors, especially diabetics with poor metabolic control, a long duration of the disease, and extensive subgingival calculus. Under managed care, there has been an expansion of soft tissue management programs in the offices of general dentists and referral guidelines which limit referral of patients with moderate periodontitis. Quality-assurance mechanisms will be essential for the diagnosis and treatment of persons with periodontitis.

Adolescent↗
PubMed1997

The differential regulation and secretion of proteinases from fetal and neonatal fibroblasts by growth factors.

One of the major differences between fetal and adult wound repair is the unique ability of fetal wounds to heal without scarring. Since scar formation is a function of extracellular matrix deposition, the regulation of this component is fundamental in tissue remodeling. In this study, we have characterized the differences in the secretion of matrix-degrading proteases, namely urokinase plasminogen activator and gelatinase A and B, from fetal and neonatal fibroblasts. In addition, we examined the modulation of these protease levels by growth factors known to be important in wound repair. The results indicate that the secretion of these proteases differ significantly between the two cell types. The levels of urokinase plasminogen activator and its inhibitor were notably higher in media conditioned by neonatal fibroblasts in comparison to fetal samples. In contrast, the basal level of gelatinase A was comparable in both cell types, whilst the level of gelatinase B was elevated in the fetal fibroblasts. Transforming growth factor-beta 1 reduced the level of urokinase plasminogen activator and stimulated the secretion of plasminogen activator inhibitor-1 and progelatinase B in both neonatal and fetal fibroblasts. However, only progelatinase A and an activated form of gelatinase B were significantly elevated in fetal fibroblasts. In contrast, platelet-derived growth factor stimulated urokinase plasminogen activator, its inhibitor and both gelatinase A and B, an effect which was more apparent in fetal fibroblasts. This difference in protease regulation may be reflected in the differing rate and quality of tissue remodeling observed during adult vs fetal wound repair.

Adult↗
PubMed1997

Prevalence and distribution of dental restorative materials in US Air Force veterans.

OBJECTIVES: Millions of restorative procedures are performed annually in the United States, yet very little is known about their distribution in the general population. With increasing concern about potential adverse health effects of some restorative materials, a better understanding of the extent of exposure to these materials in the population is important. The purpose of this study is to report the prevalence, patterns, and distribution of dental restorative materials in a population of male veterans. METHODS: This collaborative study with the US Air Force examined 1,166 male veterans to assess exposure to dental amalgam and other restorative materials. An inventory of dental materials in the study population was obtained through oral examinations. Dental materials were classified into five categories: (1) amalgam; (2) resin; (3) porcelain, cement, or temporary, including ionomer (PCT); (4) cast gold alloys/direct filling gold; and (5) other metals (OM). The mean age of the study participants was 52.9 years. Over 94 percent of the study participants were dentate. RESULTS: The study participants averaged 45.8 restored/replaced surfaces. Restored/replaced surfaces increased with age while the number of teeth decreased with age. The most frequently used restorative material was amalgam, averaging 19.89 surfaces per subject, followed by PCT (9.38), resins (8.99), OM (5.52), and gold (4.91). The distributions of restorative materials varied by age, arch type, and location in the mouth. CONCLUSION: The study population experienced substantial exposure to dental materials.

Adult↗
PubMed1997

Clinical features of early-onset periodontitis.

The authors estimate the prevalence of early-onset periodontitis, or EOP, in U.S. adolescents and describe the clinical features that occur at an early stage in those who have EOP. In 1986 and 1987, about 10.0 percent of African-American, 5.0 percent of Hispanic and 1.3 percent of white U.S. adolescents had EOP. Clinical features that may be useful in the early detection of EOP include overt gingival inflammation, dental calculus and a high rate of caries, restorations and tooth loss.

Adolescent↗
PubMed1997

Putative periodontal pathogens in subgingival plaque of young adults with and without early-onset periodontitis.

This study assessed the associations between putative periodontal pathogens and early-onset periodontitis (EOP) in a population of 248 subjects, 13 to 19 years of age at baseline, derived from a representative sample of U.S. young adults. The subjects were selected based on the presence or absence of attachment loss at baseline. The attachment level was assessed clinically at baseline and at a 6-year follow-up examination, and the presence of 7 bacterial species was assessed at follow-up using DNA probes. The individuals were classified into generalized, localized, incidental EOP, and no-periodontitis groups based on the extent and severity of attachment loss; and classified as having rapid, moderate, slow, and no progression based on the rate of periodontal progression during the 6 preceding years. In the EOP groups there were significantly higher percentages of individuals with detectable levels of Porphyromonas gingivalis, Prevotella intermedia, Fusobacterium nucleatum, Campylobacter rectus, and Treponema denticola. In addition, the EOP group had significantly higher levels of these 5 microorganisms compared to the no-periodontitis group. There were also higher percentages of individuals with these species and higher levels of bacteria in the group showing disease progression than the group without progression. In a descending order of importance, P. gingivalis, T. denticola, and P. intermedia were the microorganisms significantly associated with the generalized and/or rapidly progressing disease. F. nucleatum and C. rectus were also associated with EOP, but to a lesser degree. In the present population Actinobacillus actinomycetemcomitans was not significantly associated with EOP, though it was recovered more often from subjects with localized EOP. Eikenella corrodens was present equally in subjects with and without disease. The results show that several bacterial species are associated with EOP, and that P. gingivalis and T. denticola are of particular importance and may play a significant role in the more severe and progressive forms of EOP.

Adolescent↗
PubMed1997

Clinical classification of periodontitis in adolescents and young adults.

THE AIM OF THIS STUDY was to determine the degree to which clinical classifications based on cross-sectional assessments endure in the course of development of early-onset periodontitis (EOP), and to introduce new criteria which might improve the clinical classification of these diseases. Subjects with EOP and a matched group without EOP were identified within a national probability sample examined during the 1986/87 survey of US schoolchildren. Of these, 265 subjects (mean age 16 years) were re-examined during the 1992/93 school year. The clinical attachment level of teeth was assessed, and the individuals were classified into localized juvenile periodontitis (LJP), generalized juvenile periodontitis (GJP), incidental attachment loss (IAL), and no-periodontitis groups using three classification methods previously described. A fourth method that considered the extent and severity of attachment loss and the number of missing teeth was introduced to classify the individuals at baseline and at follow-up as having localized, generalized, or incidental EOP, and no-periodontitis groups. Furthermore, the individuals were classified using criteria based on the rate and pattern of change in attachment loss during 6 years. The results showed low correlations between the baseline classifications and the classifications at the 6-year follow-up examination, irrespective of the method used. In addition, the cross-sectional classifications were not predictive of the rate of progression of periodontal disease in these subjects. In the generalized disease group, two-thirds of the individuals exhibited moderate/rapid disease progression, while one-third had slow or no progression. In the localized disease group, one-half of the individuals had moderate/rapid disease progression and one-half had slow or no progression. In the incidental disease group one-fourth of the individuals had moderate/rapid disease progression and three-fourths had slow or no progression. We propose that the term early-onset periodontitis be used as a generic term to describe periodontal disease before its normal onset. In addition, we suggest that incidental, localized, and generalized EOP are heterogenous groups comprising rapidly and slowly progressing forms within each classification. The findings suggest that a classification system in which subsets of the disease that are defined according to a combination of cross-sectional criteria and the disease progression may be useful in studies of EOP. Furthermore, the findings suggest that clinical classifications of EOP be used as generic descriptors until a full understanding of the pathogenesis of this disease is accomplished.

Adolescent↗
PubMed1997

Fine mapping of the nail-patella syndrome locus at 9q34.

Nail-patella syndrome (NPS), or onychoosteodysplasia, is an autosomal dominant, pleiotropic disorder characterized by nail dysplasia, absent or hypoplastic patellae, iliac horns, and nephropathy. Previous studies have demonstrated linkage of the nail-patella locus to the ABO and adenylate kinase loci on human chromosome 9q34. As a first step toward isolating the NPS gene, we present linkage analysis with 13 polymorphic markers in five families with a total of 69 affected persons. Two-point linkage analysis with the program MLINK showed tight linkage of NPS and the anonymous markers D9S112 (LOD = 27.0; theta = .00) and D9S315 (LOD = 22.0; theta = .00). Informative recombination events place the NPS locus within a 1-2-cM interval between D9S60 and the adenylate kinase gene (AK1).

Chromosome Mapping↗
PubMed1996

Sequence and tissue-dependent RNA expression of mouse FAD-linked glycerol-3-phosphate dehydrogenase.

A 2432-bp cDNA for mouse FAD-linked glycerol-3-phosphate dehydrogenase, a nuclear-encoded enzyme associated with the inner mitochondrial membrane, was isolated from a Lambda ZAP phage library generated from brown adipocyte mRNA. The amino acid sequence was 95 and 93% homologous to the rat and human enzymes. PvuII and SacI polymorphisms between Mus spretus and C57BL/6J were used to map the mouse FAD-linked glycerol-3-phosphate dehydrogenase gene (Gdm1) to chromosome 2, 33 cM from the centromere. Northern blot analysis showed that brown adipose tissue predominantly expressed a 6.5-kb mRNA with lower expression of 4.5- and 2.4-kb forms, whereas brain and pancreatic islets almost exclusively expressed a 6.5-kb transcript, muscle expressed a 4.5-kb transcript, and testis expressed a 2.4-kb RNA form. Analysis of poly(A)+ RNA from brown adipose tissue suggested that all RNA forms are polyadenylated. Among the tissues examined, FAD-linked glycerol-3-phosphate dehydrogenase protein levels and enzyme activity were highest in brown adipose tissue, and a consistent correlation between protein levels and enzyme activity in all tissues was observed. RNA levels corresponded to protein levels in all tissues except testis, where high levels of 2.4-kb mRNA and relatively low protein were expressed. Exposing mice to cold temperatures induced the 6.5-kb mRNA and enzyme activity only in brown adipose tissue, suggesting a role for thermogenesis in this tissue. Although the molecular basis for the formation of the 6.5- and 4.5-kb mRNA's is not known, data suggest that the regulation of FAD-linked glycerol-3-phosphate dehydrogenase is complex and tissue-specific.

Adipose Tissue, Brown↗