Systematic search for uniparental disomy in early fetal losses: the results and a review of the literature.

About 20% of all human conceptuses are estimated to be trisomic and trisomy of all chromosomes remains a common cause of early fetal loss. Uniparental disomy (UPD) has been reported for most human chromosomes and may be an underrecognized contributor to embryonic lethality. To investigate the contribution of UPD to spontaneous abortions, we devised a genome-based screening strategy to identify holochromosomic UPD in 18 fetal losses. No cases of UPD were identified using this approach. Based on our data, UPD does not appear to be a significant contributor to early embryonic lethality. The results of the study are presented along with a review of the cases of UPD reported in the literature by chromosome, parental origin, mode of ascertainment, and phenotypic consequences due to imprinting.

Glucocorticoid regulation of GM-CSF: evidence for transcriptional mechanisms in airway epithelial cells.

Inflammation plays a central role in the pathogenesis of asthma. Glucocorticoids are first-line anti-inflammatory therapy in the treatment of asthma and are effective inhibitors of inflammatory cytokines. Clinical data demonstrate that granulocyte-macrophage colony-stimulating factor (GM-CSF) production by airway epithelial cells may be an important target of inhaled glucocorticoid therapy. We examined the regulatory mechanisms of GM-CSF expression by interleukin-1beta (IL-1beta) and the synthetic glucocorticoid dexamethasone in the BEAS-2B human bronchial epithelial cell line. IL-1beta stimulation resulted in a 15-fold induction of GM-CSF protein, which was associated with a corresponding 47-fold maximal induction of GM-CSF mRNA levels. Treatment with the transcriptional inhibitor actinomycin D before IL-1beta stimulation completely abolished induction of GM-CSF mRNA, whereas incubation with cycloheximide had no effect. Taken together, these data demonstrate that IL-1beta induction of GM-CSF is mediated through transcriptional mechanisms. Dexamethasone treatment of BEAS-2B cells produced an 80% inhibition of IL-1beta-induced GM-CSF protein and a 51% inhibition of GM-CSF mRNA. GM-CSF mRNA was rapidly degraded in these cells, and dexamethasone treatment did not significantly affect this decay rate. We conclude that, in the BEAS-2B bronchial epithelial cell line, IL-1beta induction and dexamethasone repression of GM-CSF expression are mediated predominantly through transcriptional mechanisms.

Glucocorticoid receptor signaling in a bronchial epithelial cell line.

Glucocorticoids are an effective anti-inflammatory therapy for the treatment of asthma. The anti-inflammatory effects of glucocorticoids may be due to the inhibition of transcription factors that regulate cytokine synthesis. Because of the potential role of the bronchial epithelium in asthmatic inflammation and the possibility that this cell may be the main target of inhaled glucocorticoids, we have characterized glucocorticoid receptors (GR) and GR signaling in the human bronchial epithelial cell line BEAS-2B. Western blot analysis and radioligand binding studies demonstrated that BEAS-2B cells have functional GR that bind to dexamethasone (Dex) (dissociation constant = 5.6 nM and maximal density of binding sites = 228 +/- 3.3 fmol/mg protein). GR were activated by Dex as assessed using a glucocorticoid-responsive reporter plasmid. Transfection of BEAS-2B cells with an activator protein-1 (AP-1) reporter construct followed by 12-O-tetradecanoylphorbol-13-acetate (TPA) treatment resulted in a fivefold induction of reporter gene activity. Transfection with a nuclear factor (NF)-kappa B reporter construct followed by tumor necrosis factor-alpha (TNF-alpha) treatment resulted in a 10-fold induction of reporter gene activity. Dex (10(-7) M) markedly repressed both the induced AP-1 and NF-kappa B activity. The GR antagonist RU-486 inhibited the repressive effect of Dex on TNF-alpha-induced NF-kappa B activity by 81% but only counteracted the repressive effect of Dex on TPA-induced AP-1 activity by 43%. These studies demonstrate that cross-signaling between AP-1 and NF-kappa B with GR may explain the anti-inflammatory properties of glucocorticoids in airway epithelial cells.

Perfectionism and suicidal preoccupation.

One hundred twenty-nine undergraduate students were assessed for suicidal preoccupation, using the Alabama Adolescent Health Survey (AAHS) and selected cards from the Thematic Apperception Test (TAT). They were also administered the Multidimensional Perfectionism Scale (MPS) to assess perfectionistic tendencies. Objective scoring of the TAT was found to be highly reliable. Canonical correlational analyses were nonsignificant for a relationship between perfectionism and suicidal themes on the TAT. However, the more direct questions of the AAHS relating to suicide were significantly related to perfectionism. Results suggest that passive perfectionists who procrastinate out of fear of making mistakes are more likely to be preoccupied with suicide, unlike perfectionists whose strivings produce achievement. High personal standards and parental expectations do not appear related to suicidal preoccupations.

Recombination and maternal age-dependent nondisjunction: molecular studies of trisomy 16.

Trisomy 16 is the most common human trisomy, occurring in > or = 1% of all clinically recognized pregnancies. It is thought to be completely dependent on maternal age and thus provides a useful model for studying the association of increasing maternal age and nondisjunction. We have been conducting a study to determine the parent and meiotic stage of origin of trisomy 16 and the possible association of nondisjunction and aberrant recombination. In the present report, we summarize our observations on 62 spontaneous abortions with trisomy 16. All trisomies were maternally derived, and in virtually all the error occurred at meiosis I. In studies of genetic recombination, we observed a highly significant reduction in recombination in the trisomy-generating meioses by comparison with normal female meioses. However, most cases of trisomy 16 had at least one detectable crossover between the nondisjoined chromosomes, indicating that it is reduced--and not absent--recombination that is the important predisposing factor. Additionally, our data indicate an altered distribution of crossing-over in trisomy 16, as we rarely observed crossovers in the proximal long and short arms. Thus, it may be that, at least for trisomy 16, the association between maternal age and trisomy is due to diminished recombination, particularly in the proximal regions of the chromosome.

Early cellular events in an actinomycin D-created dentin niche in the rat incisor.

Administration of actinomycin D at a dose level of 0.375 microgram/g resulted in the selective disruption of developing odontoblasts at a critical stage of morphogenesis. A dentin niche was formed which was later repaired by cellular reparative dentin. The cellular changes which resulted in dentin niche formation were studied histologically and ultrastructurally in serial longitudinal and transverse sections from tissues obtained 10 h to 80 h following injection of the drug. Five stages were identified: initial destruction (10-20 h), rapid destruction (30-40 h), debris removal (50-60 h), proliferation (60-80 h) and matrix deposition (post 80 h). The cellular changes found in the dental papilla were considerably different from those found in inflammation, resolution and repair of fibrous connective tissue. These early stages were dominated by apoptosis and heterophagy, and after 80 h by disordered dentin matrix formation. The three-dimensional morphology of the defect was reconstructed from serial sections. The shape of the niche was the result of interference by actinomycin D in the patterns of proliferation and migration of the cells in the apical region of the rat incisor tooth.

Increased sensitivity to mechanical ventilation after surfactant inactivation in young rabbit lungs.

OBJECTIVES: To study the individual and combined effects of surfactant inactivation and mechanical ventilation on pulmonary microvascular permeability and lung compliance. DESIGN: Prospective, controlled trial. An isolated, perfused, lung model of surfactant inactivation and mechanical ventilation at 15, 30, and 45 cm H2O peak inspiratory pressure was developed in young (4 to 6 wks) New Zealand white rabbits. SETTING: Laboratory of a university-affiliated medical school. MEASUREMENTS AND MAIN RESULTS: Isolated, perfused lungs were prepared for measurement of the capillary filtration coefficient before and after one of four interventions: instillation of dioctyl succinate, a surfactant inactivator, without ventilation (group 1); ventilation without dioctyl succinate at 15, 30, or 45 cm H2O peak inspiratory pressure (group 2); ventilation after dioctyl succinate pretreatment at 15, 30, or 45 cm H2O peak inspiratory pressure (group 3); and control lungs without dioctyl succinate or ventilation (group 4). A significant increase in the capillary filtration coefficient was noted after dioctyl succinate treatment alone, after ventilation alone at 45 cm H2O peak inspiratory pressure, and after dioctyl succinate plus ventilation at 15, 30, and 45 cm H2O peak inspiratory pressure. Dioctyl succinate plus ventilation produced a significantly greater increase in the capillary filtration coefficient than ventilation alone at 15 and 45 cm H2O peak inspiratory pressure. CONCLUSIONS: These data suggest that ventilation after surfactant inactivation is more injurious to the pulmonary microvasculature than ventilation alone, and that generalized lung overdistention is not the primary mechanism for microvascular injury in the diseased, noncompliant lung. The increases seen in the capillary filtration coefficient in postventilated surfactant inactivated lungs, even at low-ventilation pressures, suggest that low peak inspiratory pressures do not overdistend the dioctyl succinate-treated lung.

Dentistry--who is in charge? Workforce and training.

The quality of dental schools and of dental education in the 1990s will continue to influence the stature of the workforce and of the profession well into the 21st century. Undergraduate and postgraduate enrollments and related recurrent funding in universities are determined by the Department of Employment, Education and Training which identifies national priority areas, particularly those with export earning potential, for preferential development. Dental schools have not benefited from these initiatives. Political agendas will be increasingly important in altering the emphasis toward education and health in the future, and leaders of the profession must actively seek greater involvement with authorities and committees which are advisory to governments.

Pigmentary changes in rat oral mucosa following antimalarial therapy.

Pharmacogenic pigmentation of the oral mucosa has been reported following the use of a number of anti-malarial drugs. The nature and distribution of the pigment is inconclusive in the literature. The aim of the present study was to document pigment deposition within the oral mucosa of DA rats following prolonged chloroquine and pyrimethamine administration. The drugs were given as a combined dosage and separately to different groups via stomach gavage tube. After 12 weekly administrations the palatal mucosa was examined histochemically and ultrastructurally for changes in numbers and size of active melanocytes using the dopa-oxidase technique. The serum was analysed for changes in ACTH and testosterone levels. Morphometric analysis of cells incubated for dopa-oxidase showed a significant increase in the size of dopa positive cells with both drugs but an increase in the number of active melanocytes with chloroquine only. Serum levels of ACTH remained unchanged with both drugs but pyrimethamine caused an elevation in testosterone.

An histological study of cystic lesions following pulp therapy in deciduous molars.

The clinical and radiographic features of a group of apical periodontal cysts associated with endodontically treated deciduous molar teeth have been previously reported. The histological description and histochemical investigation of distinctive intraepithelial inclusions are described in this paper. The chronic inflammatory response is dominated by plasma cells and the wall contains an amorphous, eosinophilic material that is shown to contain phenolic groupings similar to those present in the intracanal medicaments used clinically. A direct relationship is proposed between the inclusions, continued antigenic stimulation within the lesions and their clinical behaviour.