The performance of bonded magnets used in the treatment of anterior open bite

This investigation examined the magnetic flux and repulsive force of neodymium-iron-boron (Nd-Fe-B) magnets based on Nd2Fe14B with acrylic coatings in different orientations. The flux was measured with a Hall probe and the force measured by electronic scales with the magnets mounted on a laboratory jack. Results show that there were no magnetic losses after embedding the magnets in acrylic bite-blocks, although there were significant flux losses when the magnet blocks were directly heated. The alignment of the magnets over each other was of the utmost importance and significantly affected the repulsive force between the magnets. When the magnets were mounted in an articulator to simulate jaw movement, the force levels between the magnets was further reduced as a result of the effects of the rotation of the articulator. It is concluded that Nd-Fe-B type magnets embedded in acrylic can be used to give predictable repulsive forces in the mouth. The dramatic reduction in force levels when the magnets are not in optimal alignment, however, makes their effectiveness in aiding intrusion of teeth doubtful.     

The emergence of silent myocardial ischemia as the manifestation of the nitrate withdrawal syndrome in patients with ischemic heart disease

A patient is described, who was examined 1 year after surgery for mandibular cyst diagnosed as radicular near the !5 tooth and for plasty of the secondary osseous cavity with hydroxyapatite granulate. X-Ray examination revealed a cystic cavity near the roots of teeth !234. Histologic examination of tissue fragments and the remainder of hydroxyapatite granulate, obtained by cystectomy, helped diagnose a primordial cyst. Intensive bone regeneration was observed at the site of hydroxyapatite granule accumulation and fusion of the new bone with the granules to form a solid osseogranular complex. The authors recommend hydroxyapatite ceramic granules for surgical treatment of minor and medium bone defects and for corrective bone plasty.     

Detection, significance and treatment of paraprotein in patients presenting with 'idiopathic' proteinuria without myeloma

This paper describes the detection of a paraprotein in blood or urine in 12 of 260 patients with 'idiopathic' proteinuria, most of whom presented with the nephrotic syndrome. None had myeloma at presentation and only two have developed it. Initial clinical and biochemical findings did not suggest paraprotein-associated disease, total serum globulins and individual immunoglobulin levels usually being in the normal range. In seven of the 12 cases the paraprotein was detected only after repeated analysis of serum and urine specimens over months or years. Renal histopathology varied from case to case and is described in detail; amyloid deposition did not occur in patients who excreted kappa chain Bence Jones protein and was extensive in only three. One of these eventually developed myeloma. Patients were aged 27--69 years at onset and were observed without specific therapy for up to 56 months. Glomerular filtration rate tended to decline and proteinuria persisted. All patients have now been treated by a chemotherapeutic regimen consisting of 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU), cyclophosphamide, melphalan, and prednisolone, in repeated short courses. In some patients, particularly those who had kappa Bence Jones protein, there was striking improvement. Overall survival is good, eight patients being alive 17--90 months after the onset of symptoms. The importance of repeated search for paraprotein in apparently idiopathic renal disease in adults is emphasized.     

Pain in multiple system atrophy

Nijmegen breakage syndrome (NBS), a rare autosomal recessive condition also known as ataxia telangiectasia (AT) variants V1 and V2, is characterised by microcephaly, typical facies, short stature, immunodeficiency, and chromosomal instability. We report the clinical, immunological, chromosomal, and cell biological findings in 42 patients who are included in the NBS Registry in Nijmegen. The immunological, chromosomal, and cell biological findings resemble those in AT, but the clinical findings are quite different. NBS appears to be a separate entity not allelic with AT.     

Altered interface adhesion molecules in oral lichen planus

Recurrent spontaneous abortion is a frustrating problem for clinicians and their patients. Fortunately, a reasonable amount of research is being conducted to try and identify the causes of this disorder and develop appropriate and effective diagnostic tests and therapies. This review focuses on some of the factors that have been associated with recurrent abortion, such as cell-mediated immune responses to trophoblast antigens, the effect of oxidative stress, and the immunomodulatory properties of placental protein. The risk of recurrence is particularly high when the length of the embryo in early pregnancy is less than the 50th centile, even though cardiac activity may be present. Also, the risk is directly related to the number of previous abortions. Efficacy has been shown for treatment of unexplained recurrent abortion with allogeneic leukocyte immunization and possibly with intravenous immunoglobulin. Patients with oligomenorrhoea may benefit from treatment with human chorionic gonadotropin.     

The negative feedback actions of progesterone on gonadotropin-releasing hormone secretion are transduced by the classical progesterone receptor

Progesterone (P) powerfully inhibits gonadotropin-releasing hormone (GnRH) secretion in ewes, as in other species, but the neural mechanisms underlying this effect remain poorly understood. Using an estrogen (E)-free ovine model, we investigated the immediate GnRH and luteinizing hormone (LH) response to acute manipulations of circulating P concentrations and whether this response was mediated by the nuclear P receptor. Simultaneous hypophyseal portal and jugular blood samples were collected over 36 hr: 0-12 hr, in the presence of exogenous P (P treatment begun 8 days earlier); 12-24 hr, P implant removed; 24-36 hr, P implant reinserted. P removal caused a significant rapid increase in the GnRH pulse frequency, which was detectable within two pulses (175 min). P insertion suppressed the GnRH pulse frequency even faster: the effect detectable within one pulse (49 min). LH pulsatility was modulated identically. The next two experiments demonstrated that these effects of P are mediated by the nuclear P receptor since intracerebroventricularly infused P suppressed LH release but 3alpha-hydroxy-5alpha-pregnan-20-one, which operates through the type A gamma-aminobutyric acid receptor, was without effect and pretreatment with the P-receptor antagonist RU486 blocked the ability of P to inhibit LH. Our final study showed that P exerts its acute suppression of GnRH through an E-dependent system because the effects of P on LH secretion, lost after long-term E deprivation, are restored after 2 weeks of E treatment. Thus we demonstrate that P acutely inhibits GnRH through an E-dependent nuclear P-receptor system.     

Detection of telomerase activity in Chinese hamster V79 cells and its inhibition by 7-deaza-deoxy guanosine triphosphate and (TTAGGG)4 in vitro

To investigate the nature of telomerase activity and its inhibition in Chinese hamster V79 cells, we have detected telomerase activity in Chinese hamster cells using Telomeric Repeat Amplification Protocol (TRAP) assay. We have further studied inhibition characteristics of this enzyme in vitro by nucleotide analogue 7-deaza-2'-deoxy guanosine triphosphate (7-deaza-dGTP) and oligonucleotide (TTAGGG)4. Both the inhibitors inhibited the telomerase activity in a dose dependent manner. To attain 50% inhibition of the telomerase activity, we needed about 4.5 microM of 7-deaza-dGTP. Similarly, preincubation at 37 degreesC of the cell extract with 1.25 x 10(-3) microgram oligonucleotide (TTAGGG)4 showed 50% inhibition of the control value. Inhibition of telomerase activity by 7-deaza-dGTP could be due to the incorporation of the modified nucleotide in the telomeric repeat and thus altering the further binding/extension by the enzyme. (TTAGGG)4 could have possibly interacted with RNA component of telomerase and inhibited its activity.     

Albumin-binding surfaces: in vitro activity

Immobilized monoclonal antibodies (Mabs) have been used to attract specific molecules to a solid surface from complex mixtures such as blood, plasma or serum, thereby directing the response to the modified substrate, a key goal in rational biomaterial design. The nature of the Mab dictated the nature of the response: anti-albumin antibodies were used to prevent cell and platelet adhesion in vitro, whilst anti-fibronectin Mabs promoted attachment. Patterned surfaces could be formed, bearing Mabs that generated adhesive and non-adhesive regions. Fibrinogen adsorption from plasma showed a Vroman peak on unmodified control polymer, which was reduced by 64% in the presence of surface-bound anti-albumin Mab. Immobilization of a control Mab reduced fibrinogen adsorption only slightly, implying an albumin-mediated effect. In static tests, platelet adhesion from human platelet rich plasma was significantly reduced by the immobilization of anti-HSA Mab when compared to the untreated FEP surface (p < 0.0001). This effect was also seen with citrated blood flowing through Mab-treated polyurethane tubing at a shear rate of 132 s(-1) (p=0.034). Since platelets and proteins (as blood, plasma or serum) were introduced to the surface simultaneously, the generation of a defined protein film must have been sufficiently rapid as to shape the platelet or cell response.