Rationale for retention following orthodontic treatment

Maintaining the treatment result following orthodontic treatment is one of the most difficult aspects of the entire treatment process. Normal maturational changes, together with post-treatment tooth alterations, conspire against long-term stability. This article discusses the need for retention and provides an overview of retainers which enjoy widespread use.

CLINICAL SIGNIFICANCE

Permanent retention is increasingly being recommended as the only way to ensure long-term stability of an orthodontic treatment result. Dental practitioners should be familiar with the rationale for retention and the design of the appliances worn by the their patients.

Retention and stability: a review of the literature

Long-term posttreatment stability is an issue of great concern to all orthodontists. This article highlights the factors reported to play a role in posttreatment crowding and reviews the long-term retention studies evaluating the stability of various treatment modalities. Recommendations, based on well-documented basic principles, are made to try to insure greater posttreatment stability of our orthodontically treated cases.

The use of an orthodontic thermoplastic retainer as a provisional anterior restoration: a case report

Children who present with extensive fractures of anterior teeth pose a difficult clinical problem. Pulpal and periodontal injuries must be carefully assessed and managed. Rapid restoration of the form and contour of the extensively fractured tooth is advisable, not only to improve esthetics but also to prevent unwanted tipping or tilting of adjacent teeth and overeruption of opposing teeth. A modified Essix retainer, simply constructed in the laboratory, can be used to provisionally restore the extensively fractured anterior tooth.

The frail elderly in the family

Longer life expectancy, better health and higher levels of financial independence will characterise the elderly of the future. These will result in a greater variety of living and care arrangements including an increasing proportion of older people who will choose to live on their own. Caring for a frail elderly person in the family requires a change of family roles, a process often accompanied by emotional upheavals. The degree of difficulty experienced will be linked to the level of economic and physical dependence of the elderly person. Demographic changes will add new dimensions to the problems of care. In four generation families, which will be more common, the burden of care will shift to adult grand children. Fewer children and grand-children will be available to share care responsibilities. A range of commercial and welfare services will be required to meet the increasing range of needs. Careful evaluation is needed in monitoring both improvements and the risks to the frail elderly and the family in the changing scenario.

Census tract analysis of lead exposure in Rhode Island children

There has been increasing interest in a targeted approach to the screening and prevention of lead exposure in children. Targeted screening requires an understanding of variation in lead exposure in individual children or by region. In order to better understand variation by region, we studied Rhode Island lead poisoning screening data, examining average lead exposure to children living in 136 Providence County census tracts (CTs). The study population included 17,956 children aged 59 months and under, who were screened between May 1, 1992, and April 30, 1993. We evaluated the relationship between the percentage of children with blood lead > or = 10 micrograms/dL (pe10) and sociodemographic and housing characteristics, derived from United States 1990 Census data, of these CTs. CT descriptors included population density, percentage of households receiving public assistance income, median per capita income, percentage of households female headed, percentage of houses owner occupied, percentage of houses built before 1950, percentage of houses vacant, percentage of population Black, percentage of recent immigrants, and intraurban mobility. On average, 109 children were screened in each census tract; mean screening rate was 44%. There was wide variation in average lead exposure among census tracts, with pe10 ranging from 3 to 60% of screened children (mean 27%). Individual census variables explained between 24 and 67% of the variance in pe10 among CTs. A multiple regression model including percentage screened, percentage of households receiving public assistance, percentage of houses built before 1950, In (percentage of houses vacant), and percentage of recent immigrants explained 83% of variance in pe10. The percentage of houses built before 1950, a variable which models the presence of lead paint in old houses, displayed the largest adjusted effect on pe10 over the range observed for that variable in RI CTs. The percentage of houses vacant was also a highly significant and robust predictor; we suggest that vacancy is an ecological marker for the deterioration of leadbased paint, with higher vacancy neighborhoods containing houses in poorer condition. In Rhode Island, census tracts with high vacancy rates also have high rates of recent immigration, making immigrant groups vulnerable to lead exposure. Small-areas analysis may be useful in directing resources to high risk areas, explaining the sociocultural forces which produce such exposure and analyzing the effects of housing policy over time in states with high screening penetration.

Interactions of the transcription factors MIBP1 and RFX1 with the EP element of the hepatitis B virus enhancer

We previously demonstrated that MIBP1 and RFX1 polypeptides associate in vivo to form a complex that binds to the MIF-1 element in the c-myc gene and the major histocompatibility complex class II X-box recognition sequence. We now show that the EP element, a key regulatory sequence within hepatitis B virus enhancer I, also associates with MIBP1 and RFX1. Using polyclonal antisera directed against either oligonucleotide-purified MIBP1 or a peptide derived from the major histocompatibility complex class II promoter-binding protein RFX1, we showed that MIBP1 and RFX1 are both present in the DNA-protein complexes at the EP site. In addition, while the EP element can act cooperatively with several adjacent elements to transactivate hepatitis B virus expression, we demonstrated that the EP site alone can repress transcription of simian virus 40 promoter in a position- and orientation-independent manner, suggesting a silencer function in hepatocarcinoma cells.

Large-scale selection of CD34+ peripheral blood progenitors and expansion of neutrophil precursors for clinical applications

Hematopoietic recovery after high-dose chemotherapy is characterized by an obligate period of neutropenia of approximately 8-10 days. It is postulated that if a pool of neutrophil precursors and progenitors were expanded in vitro and reinfused, the duration of neutropenia may be substantially shortened by these cells capable of providing mature neutrophils within days of reinfusion. In this study, peripheral blood progenitor cell products were obtained from six normal donors mobilized with rhG-CSF and two patients mobilized with cyclophosphamide and rhG-CSF. CD34+ cells were isolated using the Isolex immunomagnetic bead method. A mean of 8.26 x 10(7) CD34+ cells with a mean purity of 74.5% were seeded at a concentration of 1 x 10(5)/ml into a 12 day stroma-free liquid culture using gas-permeable bags. A serum-free growth medium supplemented with PIXY321 was used. On day 7, there was a mean cellular expansion of fourfold, at which time the cells were resuspended at the initial concentration, yielding a mean culture volume of 3L (1-6 L). On day 12, there was an additional mean fold cellular expansion of 10 x, achieving an overall mean fold expansion of 41 +/- 16. Cellular characterization of the expanded cells revealed predominantly neutrophil precursors by morphology (mean 70.1%) and flow cytometric analysis. A mean of 52.3% of the expanded cells expressed CD15. Immunohistochemical staining revealed a mean of 7.1% CD41a+ megakaryocytic progenitors in the final cultured cell product. Detectable CD34+ cells were maintained only in those cultures initiated with greater than 90% CD34+ cells. Colony-forming units-granulocyte-macrophage (CFU-GM) were maintained in the 12 day culture at a level similar to the preculture number, whereas CFU mixed were depleted in all samples. On day 0, there were few CFU clusters (colonies containing fewer than 50 cells) identified, but by day 12, a mean total of 8.3 x 10(6) CFU clusters were identified. On day 12, the expanded cells were harvested and pooled using the Fenwal CS3000 Plus blood cell separator and resuspended in Plasma-Lyte-A with 1% human serum albumin. The mean harvest recovery of expanded progenitors was 91%, with a mean viability of 86%.

Selection and expansion of peripheral blood CD34+ cells in autologous stem cell transplantation for breast cancer

Cytopenia after high-dose chemotherapy and autologous stem cell reinfusion is a major cause of morbidity. Ex vivo cultured expansion and differentiation of CD34+ peripheral blood progenitor cells (PBPC) to neutrophil precursors may shorten the neutropenic period further. We explored the use of these ex vivo cultured PBPCs in nine patients with metastatic breast cancer. All underwent PBPC mobilization with cyclophosphamide, VP-16, and G-CSF. Subsequently, they underwent four to five apheresis procedures. One apheresis product from each patient was prepared using the Isolex 300 Magnetic Cell Separation System (Baxter Immunotherapy, Irvine, CA) to obtain CD34+ cells. These cells were then cultured in gas permeable bags containing serum-free X-VIVO 10 (BioWhittaker, Walkersville, MD) medium supplemented with 1% human serum albumin and 100 ng/mL PIXY321. At day 12 of culture the mean fold expansion was 26x with a range of 6 to 64x. One patient's cells did not expand because of a technical difficulty. The final cell product contained an average of 29.3% CD15+ neutrophil precursors with a range of 18.5% to 48.1%. The patients underwent high-dose chemotherapy with cyclophosphamide, carboplatin, and thiotepa. On day 0, the cryopreserved PBPCs were reinfused and on day +1 the 12-day cultured cells were washed, resuspended, and reinfused into eight of nine patients. One patient was not infused with cultured cells. The mean number of cultured cells reinfused was 44.6 x 10(6) cells/kg with a range of 0.8 to 156.6 x 10(6) cells/kg. No toxicity was observed after reinfusion. The eight patients have recovered absolute neutrophil counts > 500/microL on a median of 8 days (range 8 to 10 days); the median platelet transfusion independence occurred on day 10 (range 8 to 12 days) and platelet counts > 50,000/microL were achieved by day 12 (range 9 to 14) for the seven patients whose platelet counts could be determined. Expanded CD34+ selected PBPC can be obtained and safely reinfused into patients.

Clinical use of selected and expanded peripheral blood CD34+ cells: a preliminary report of feasibility and safety

In this report, we describe the preliminary results from a feasibility and safety study on the clinical use of CD34-positive cells cultured from mobilized peripheral blood. Separation and cell expansion were successfully performed, and the patients tolerated the infusions without problems and achieved engraftment.

Geodemographic segmentation systems for screening health data

AIM

To describe how geodemographic segmentation systems might be useful as a quick and easy way of exploring postcoded health databases for potential interesting patterns related to deprivation and other socioeconomic characteristics.

DESIGN AND SETTING

This is demonstrated using GB Profiles, a freely available geodemographic classification system developed at Leeds University. It is used here to screen a database of colorectal cancer registrations as a first step in the analysis of that data.

RESULTS AND CONCLUSION

Conventional geodemographics is a fairly simple technology and a number of outstanding methodological problems are identified. A solution to some problems is illustrated by using neural net based classifiers and then by reference to a more sophisticated geodemographic approach via a data optimal segmentation technique.

Intracytoplasmic sperm injection in dysmorphic human oocytes

Fertilisation and development of dysmorphic human oocytes recovered from hyperstimulated ovaries have been evaluated following intracytoplasmic sperm injection (ICSI) for treatment of male infertility. A total of 2968 oocytes at metaphase II of meiosis were injected, of which 806 (27.2%) were dysmorphic at the light microscopic level. Cytoplasmic abnormalities included granularity, areas of necrosis, organelle clustering, vacuoles, and accumulating saccules of smooth endoplasmic reticulum. Anomalies of the first polar body and zona pellucida, as well as non-spherical shapes of oocytes, were also noted. Contrary to previous findings linking some dysmorphisms to non-assisted fertilisation failure, in this study no single abnormality led to a reduction in the fertilisation rate, nor was fertilisation compromised in oocytes with multiple abnormalities. The incidence of normal fertilisation (two pronuclei and two polar bodies) was 69% in both the dysmorphic and non-dysmorphic oocytes. While overall pregnancy and implantation results were not altered in the group of patients (n = 242) in whom at least one dysmorphic oocyte was injected, exclusive replacement of embryos which originated from dysmorphic oocytes led to a higher incidence of early pregnancy loss. It is concluded that aberrations in the morphology of human oocytes--most probably a product of controlled ovarian stimulation--are of little or no consequence to fertilisation or early cleavage after ICSI. It is possible, however, that these embryos have a reduced potential for implantation and further development.

The N-terminal domain of c-Myc associates with alpha-tubulin and microtubules in vivo and in vitro

The polymerization of alpha- and beta-tubulin into microtubules results in a complex network of microfibrils that have important structural and functional roles in all eukaryotic cells. In addition, microtubules can interact with a diverse family of polypeptides which are believed to directly promote the assembly of microtubules and to modulate their functional activity. We have demonstrated that the c-Myc oncoprotein interacts in vivo and in vitro with alpha-tubulin and with polymerized microtubules and have defined the binding site to the N-terminal region within the transactivation domain of c-Myc. In addition, we have shown that c-Myc colocalizes with microtubules and remains tightly bound to the microtubule network after detergent extraction of intact cells. These findings suggest a potential role for Myc-tubulin interaction in vivo.

After care program II: a volunteer's perspective

This article presents a volunteer's reflections on the Trauma Support After Care Program at Hartford Hospital. The support given to families who have suffered a tragic loss is described, as is the satisfaction a volunteer experiences in providing support for both the program and the families.

A radiographic comparison of apical root resorption after orthodontic treatment with the edgewise and Speed appliances

Apical root resorption is a serious iatrogenic problem sometimes associated with orthodontic treatment. The Speed appliance (Strite Industries, Ltd., Ontario, Canada) provides a continuous rotatory and torque action through its spring clip mechanism, in contrast with the edgewise appliance that may provide an interrupted force. The effect of continuous action on root resorption compared with the interrupted action of the edgewise system has not been investigated previously. The purpose of the present investigation is to test the null hypothesis that there is no difference in the apical root resorption seen after orthodontic treatment with the edgewise straight wire and the Speed appliance systems. Pretreatment and posttreatment periapical radiographs of 63 patients, (30 treated with the Speed 0.018 bracket and 33 with the 0.018 edgewise bracket) were studied. The long cone paralleling technique was used for all the radiographs. Any image distortion between the pretreatment and posttreatment radiograph was calculated and compensated for by using the crown length measurements, on the assumption that the crown length remains unaltered during the treatment period. Quantitative measurements of crown and root lengths for the maxillary and the mandibular central and lateral incisors were compared. Means and standard deviations for the percentage root resorption per tooth group were calculated. A three-factor analysis for variance (ANOVA test) was performed to determine whether there was an appliance, treatment, or gender effect on the amount of root resorption seen after treatment. No statistically significant difference in root resorption between the two appliance systems was found.(ABSTRACT TRUNCATED AT 250 WORDS)

The myc intron-binding polypeptide associates with RFX1 in vivo and binds to the major histocompatibility complex class II promoter region, to the hepatitis B virus enhancer, and to regulatory regions of several distinct viral genes

We demonstrated that MIF-1, identified initially as a binding activity that associated with the intron I element of the c-myc gene, consists of two polypeptides, the myc intron-binding peptide (MIBP1) and the major histocompatibility class II promoter-binding protein, RFX1. Using a polyclonal antiserum directed against either oligonucleotide affinity-purified MIBP1 or a peptide derived from RFX1, we showed that MIBP1 and RFX1 are distinct molecules that associate in vivo and are both present in DNA-protein complexes at the c-myc (MIF-1) and major histocompatibility complex class II (RFX1) binding sites. We have also found that MIBP1 and RFX1 bind to a regulatory site (termed EP) required for enhancer activity of hepatitis B virus. In addition, we have identified MIF-1-like sequences within regulatory regions of several other viral genes and have shown that MIBP1 binds to these sites in cytomegalovirus, Epstein-Barr virus, and polyomavirus. We have also demonstrated that the MIF-1 and EP elements can function as silencers in the hepatocarcinoma HepG2 and the cervical carcinoma HeLa cell lines. These findings indicate that MIBP1 and EP/RFX1 can associate in vivo and may regulate the expression of several distinct cellular and viral genes.

Constructing regions for small area analysis: material deprivation and colorectal cancer

BACKGROUND

This paper is about constructing small areas for the analysis of health data with the aims of health service delivery in mind. The areal framework should enable the analyst to link health data and census data and the areas should have large enough populations to ensure that rates are reliable and be homogeneous with respect to important socio-economic attributes.

METHODS

An information-based statistic is used for the construction of regions in Sheffield based on the Townsend deprivation index. Enumeration districts are used as the geographical building blocks for the regions. The new regional framework is used for computing Bayes adjusted standardized incidence rates for colorectal cancer (CRC) across Sheffield. The paper then examines the statistical relationship between CRC incidence and deprivation across the set of regions using bivariate regression.

RESULTS

The method yields regions that are considerably more homogeneous in terms of deprivation than wards, and using this framework it is shown that there is a (weak) statistical association at the regional scale between deprivation and CRC.

CONCLUSION

We conclude that statistical tools can be employed to provide regions that meet the criteria for small area analysis of health data and the analyst does not have to be tied to large administrative units such as wards. There are some benefits to executing this work within a Geographic Informative System. The method should be of interest to those concerned with health service delivery and the identification of 'problem regions'.

Electron beam intraoperative radiation therapy for pediatric neoplasms

BACKGROUND

Intraoperative radiation therapy (IORT) has potential advantages over conventional external beam radiation in that a single large dose is delivered to the tumor and its regional bed at the time of surgical exploration. The therapeutic ratio is enhanced by direct tumor visualization, precise treatment volume, and exclusion of normal organs. In childhood, local tumor control is critical for lesions that cannot be totally excised or residual disease not ablated by systemic therapy.

METHODS

During the past decade, the authors evaluated IORT in pediatric patients with unresectable or recurrent tumors. Fifty-nine patients were treated, 48 for advanced malignant disease and 11 for histologically benign but locally aggressive tumors. Sixty-four operations were performed, during which 84 separate radiation fields were used. High energy electrons at 5-11 MeV were delivered at a dose of 1000-1700 cGy to a tissue depth of 0.5-3 cm.

RESULTS

Of 25 children with advanced neuroblastoma, 15 were alive 14-104 months (mean, 51 months) after treatment. The survival of all patients with solid malignancies was 63%. Local tumor control was achieved in 75% of children with cancer and 91% of those with benign tumors. Complications of IORT at the doses used were trivial.

CONCLUSIONS

Electron beam therapy can be safely and efficiently delivered to young patients during operations intended to treat the primary tumor. The outcome achieved for overall survival and local control of the primary tumor is encouraging, and an acceptable complication rate during intermediate to long-term follow-up has been noted.

c-myc Down-regulation in suramin-treated HL60 cells precedes growth inhibition but does not trigger differentiation

Down-regulation of c-myc mRNA expression is linked to growth arrest and the state of differentiation of hematopoietic cells. We showed that treatment of HL60 cells with suramin results in a rapid reduction of c-myc expression followed by an inhibition of cell growth. Both c-myc mRNA and protein levels decreased by day 1 of treatment, and, by day 4, only 10% of control c-myc protein levels were detected. In contrast to retinoic acid, dimethyl sulfoxide, and 12-O-tetradecanoylphorbol-13-acetate treatment, however, exposure of HL60 cells to suramin did not result in the induction of differentiation. These results demonstrate that suramin modulates c-myc levels in HL60 cells and that the down-regulation of c-myc is not sufficient to trigger differentiation toward either granulocytic or monocytic lineages.

Comparative study of the survival rate of frozen-thawed embryos with perforated zonae from microsurgical fertilization and frozen-thawed embryos with intact zonae

OBJECTIVE

To compare the survival rate of frozen-thawed embryos with perforated zonae from microsurgical fertilization (subzonal insemination) (SUZI) with that of embryos with intact zonae.

DESIGN

Thirty-eight embryos resulting from microsurgical fertilization by SUZI were cryopreserved in 16 patient cycles. Within the same period, 140 zonae-intact embryos from 46 patient cycles were cryopreserved. The survival rate of the SUZI embryos was compared with the zonae-intact embryos after thawing. Clinical pregnancies were compared after the transfer of the thawed embryos.

RESULTS

The total survival rates were 94.7% and 89.3% for thawed SUZI embryos and zonae-intact embryos, respectively. Within each type of embryo, total survival rates were similar irrespective of the age of the embryos at freezing. The blastomere loss per thawed embryo was the same for zonae-intact and SUZI embryos. One clinical pregnancy was obtained in patients who received thawed SUZI embryos and nine in patients who received embryos with intact zonae.

CONCLUSIONS

It is concluded that SUZI embryos can be cryopreserved and thawed with the same degree of confidence as zonae-intact embryos. The low implantation rate of thawed SUZI embryos requires confirmation in a larger clinical series.

Immunogenicity and evolutionary variability of epitopes within IgA1 protease from serogroup A Neisseria meningitidis

Five murine epitopes were defined and mapped within IgA1 protease produced by Neisseria meningitidis. Epitopes 1 and 2 were present in IgA1 protease from all strains, and from Neisseria gonorrhoeae. Epitopes 3 through to 5 varied between subgroups of serogroup A meningococci, but have remained constant over decades within the subgroups, except for epitope 4, which changed between 1983 and 1987 during the spread of subgroup III meningococci from Asia to Africa. Binding of monoclonal antibodies to epitopes 1, 4 and 5 neutralized enzymatic function. Human sera containing antibodies to IgA1 protease as a result of natural infection inhibited binding of monoclonal antibodies to epitope 4 but not to the other epitopes.