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A report of orthodontic undergraduate education in two dental schools: Toronto, Canada and Liverpool, England.

The undergraduate orthodontic courses at Toronto and Liverpool are compared. Each course comprises more than 250 hours of teaching and within that, more than 100 hours involve clinical tuition. Both courses contain laboratory modules for the teaching of removable and fixed appliance technique. Undergraduates treat their own patients with both simple and complex appliances, within their clinical training period which extends over at least 2 years. Liverpool undergraduates treat more patients per student than their counterparts in Toronto (P < 0.05). During the third year of study, the clinical experience of the Liverpool students (P < 0.001) is made up of a greater proportion of patients treated with removable appliances. In both centres, senior students treat patients with a greater preponderance of fixed appliance techniques and two-arch treatments.

Canada↗

Facial aesthetics following edgewise and Fränkel appliance therapy: the application of Chernoff faces.

This study investigates an application of the graphical technique of multivariate data description, 'Chernoff faces', to orthodontics. This method of pictorial presentation allows the simultaneous examination of several measurements in a single figure. Each variable is represented by a scaled feature of the human face: the size and position of the ears, eyes, eyebrows, nose, and mouth, as well as the face itself, are used to display data in a diagrammatic form. Using this method, the individual post-treatment results of 62 severe Class II division 1 cases treated by either Fränkel or Edgewise appliance therapy were compared. Nine cephalometric variables were chosen, describing the profile and the antero-posterior positions of the lower jaw and teeth, and stylized cartoon faces drawn for each child. These were compared with a control face prepared from untreated children of the same sex and age. Overall, children treated with Fränkel appliances showed a more normal relationship of the lips to Ricketts' aesthetic line and a greater prominence of the lower face. This difference between the two groups was most marked in the soft tissues. In a few cases, however, the appearance of the Edgewise treated children was indistinguishable from that of the controls. It is concluded that Chernoff faces, by portraying several pertinent aspects of data simultaneously, may be a useful adjunct to the presentation of orthodontic findings.

Adolescent↗

Partial glossectomy for the treatment of anterior open bite. A case report.

A 24-year-old Afro-Caribbean with a pronounced anterior open bite and bimaxillary protrusion was successfully treated to a stable result with a partial glossectomy and fixed appliance therapy. Although transient sialorrhea and paraesthesia were experienced post-operatively, speech and function showed some improvement 2 years after treatment.

Adult↗

Patterns of circulating hepatitis B virus serum nucleic acids during lamivudine therapy.

Lamivudine treatment of individuals with chronic HBV infection leads to a rapid decline of hepatitis B virus (HBV) serum DNA. Because HBV replication quickly reaches pretreatment values following cessation of the drug, we addressed the question of whether changes during therapy in composition and amount of discernible circulating viral DNA and RNA might provide an explanation for this phenomenon. Nucleic acids were extracted from serial serum samples of two chronically infected patients. The first patient was treated with lamivudine for 14 weeks, whereas the second one, who displayed an HBV virus with a core gene mutation, received lamivudine for 10 weeks. Three sequence segments of the HBV genome synthesized successively during replication, namely, X, C, and X-preC, were analyzed via competitive polymerase chain reaction (PCR) and reverse transcriptase (RT)/PCR. HBV transcripts were also analyzed for differential polyadenylation. At the start of treatment, identical DNA copy numbers (10(9)/mL) were found for all three segments in the first patient. C segment DNA displayed the expected rapid decline. X-preC, a target contiguous only on plus-strand DNA, behaved similarly. In contrast, the X segment DNA copy numbers showed a less pronounced decrease, remaining at higher values (10(7)/mL) than the C and X-preC segments (both about 2 x 10(5)/mL) at the end of therapy. X segment RNA displayed a persisting copy number of about 10(7)/mL, whereas C and X-preC RNA decreased to about 10(5) copies/mL. Polyadenylated HBV RNA, both full-length and truncated, initially persisted at 10(5) but decreased to 10(4) to 10(3) copies/mL at the end of treatment. As expected, C segment DNA and RNA were not detected in the second patient, whereas X and X-preC segments showed essentially the same pattern as the first patient, although at a slightly lower level. We conclude that: (1) actual numbers of HBV genome equivalents during lamivudine therapy can be assessed only via X segment DNA, because it is reverse transcribed first; (2) lamivudine induces coexistence of DNA and RNA for the C and X segments at similar levels, indicating drug-arrested intermediates of reverse-transcribed HBV DNA minus-strand; and (3) packaged HBV RNA lacks a poly(A) tail, whereas polyadenylated RNA is likely not packaged.

Antiviral Agents↗

A thymoma as a cause of true ectopic hyperparathyroidism.

Ectopic tumoral secretion of authentic PTH is rare, as only four cases have been convincingly documented by demonstrating the presence of PTH messenger ribonucleic acid in tumor tissue. We report the case of a 25-yr-old male with biochemical alterations typical of primary hyperparathyroidism (elevated calcemia and renal tubular reabsorption of calcium, decreased phosphatemia and maximal tubular reabsorption of phosphate, and increased intact PTH serum levels). Extensive cervical exploration did not reveal any abnormally enlarged parathyroid tissue, but excision of a palpable superior retrosternal mass led to the correction of all abnormal biochemical values. Histological analysis showed a predominantly epithelial thymoma, without any detectable parathyroid gland on serial slices. Tumor extracts contained immunoreactive PTH material, with serial dilutions paralleling PTH standards in an immunoradiometric assay. By contrast, immunoreactive PTH-related protein was absent. Furthermore, on Northern blot analysis, there was a PTH messenger ribonucleic acid transcript with a size similar to that found in parathyroid adenoma or hyperplasia. The thymoma epithelial cells stained positively with antiserum against PTH-(1-34), but negatively with antichromogranin-A antiserum. These results support the ectopic production of authentic PTH by a thymoma and indicate a novel tumoral cause of primary hyperparathyroidism.

Adult↗

The timing of orthodontic treatment.

The time at which orthodontic treatment should be started remains a matter of conjecture. Anomalies of dental development and functional problems tend to be addressed in the mixed dentition, while definitive treatment tends to be delayed until the late mixed dentition to maximize growth potential and patient compliance. However, some clinicians advocate starting treatment earlier in certain types of malocclusion. In this article, the current concepts of early treatment, both physiological and psychological, will be explored and the relevant indications and contraindications discussed.

Adolescent↗

Androgenic control of immunoreactive somatostatin in the Harderian gland of the Syrian hamster.

Harderian glands of Syrian hamsters contained measurable levels of immunoreactive somatostatin. After an extraction procedure, serial dilutions of tissue were assayed and showed parallelism in the displacement curve with dilutions of purified somatostatin standard in the radioimmunoassay. Somatostatin concentrations were higher in female hamsters (10.0 +/- 2.1 ng/mg protein) than in males (2.6 +/- 0.4 ng/mg protein). Castrated males had somatostatin values in the range of females (12.4 +/- 2.3 ng/mg protein) at 1 month after gonadectomy. Testosterone implants prevented the rise of Harderian gland somatostatin in castrated males. Gonadectomized males had lower somatostatin content in the gland than did control males (1.0 +/- 0.2 ng/mg protein) at 2 months after castration. Somatostatin values in females were unaffected by gonadectomy, but there were variations during the oestrous cycle, with a nadir detected at dioestrus-1 and maximal values coincident with the day of the ovulation.

Androgens↗

Determination of gizzerosine activity in fish meal with a homologous radioimmunoassay.

A homologous RIA for the determination of toxic gizzerosine activity in commercial fish meals has been developed. Three polyclonal antibodies (GR316, GR415, and GR418) were produced in female rabbits and extensively characterized for their potential use in individual RIA. The RIA had lower detection limits of 0.048, 0.78, and 0.39 ng/mg using the three respective antibodies. Because gizzerosine is derived from lysine and histidine, crossreactivity with these amino acids, and with histamine was examined. The antibodies crossreacted with histamine from 21 to 100%. No crossreactivity with histidine or lysine was observed for any of the three antibodies. Antibody GR415 was chosen for determination of gizzerosine in extracted fish meal samples because crossreactivity of histamine using this antibody was only present at high concentrations, and the Ka value for gizzerosine was 10-fold greater than for histamine. A mild buffer extraction procedure was used, resulting in 98% gizzerosine recovery. Displacement curves from extracted and serially diluted fish meal samples were parallel with gizzerosine standard. Inter-and intra-assay coefficients of variation were 11 and 15%, respectively. We used the RIA for determination of gizzerosine activity in a pool of 23 fish meal samples of known gizzerosine scores (determined with a chick bioassay), and histamine content. The partial correlation coefficient between gizzerosine content determined by the RIA and gizzerosine scores from the bioassay was high (0.83), and significant (P < 0.01). There were also significant correlations between gizzerosine scores and histamine content of the fish meals (0.63, P < 0.01), and between histamine content and gizzerosine levels determined by the RIA (0.59, P < 0.01). The application of the homologous RIA for the determination of gizzerosine activity in commercial fish meals could be of importance for the prevention of gizzard erosions in the poultry industry, and for studying gizzerosine-induced pathology and metabolism.

Animals↗

Heliquinomycin, a new inhibitor of DNA helicase, produced by Streptomyces sp. MJ929-SF2 I. Taxonomy, production, isolation, physico-chemical properties and biological activities.

Heliquinomycin was isolated as a part of a program designed to find inhibitors of DNA helicase from microbial sources. It was purified from the culture broth of Streptomyces sp. MJ929-SF2 by solvent extraction and serial chromatographies of centrifugal partition chromatography, Sephadex LH-20 and Capcell Pak C18 (HPLC). The isolated red powder was analyzed to have the molecular formula of C33H30O17. It inhibited partially purified DNA helicase from HeLa cell in a non-competitive manner with the inhibition constant (Ki) of 6.8 mM. Heliquinomycin exhibited biological activity against microorganisms including MRSA, and cultured cell lines.

Animals↗