Ethylene production from methionine

1. A new reaction is described in which ethylene is formed from the Cu(+)-catalysed breakdown of methionine in phosphate buffer at 30 degrees in air. Some of the other products of the reaction are methionine sulphone, methionine sulphoxide, homocysteic acid, homocystine, acrolein, dimethyl disulphide, methanethiol, ethyl methyl sulphide, methane and ethane. These are considered to be produced in different reaction pathways. 2. Hydrogen peroxide is an intermediate in this reaction and can support ethylene production in the model system in anaerobic atmospheres. Cuprous copper is the active form that catalyses the formation of ethylene from an oxidized intermediate. The initial reaction is probably a Strecker degradation, but the aldehyde product is further degraded to ethylene and other products. 3. Methional (CH(3).S.CH(2).CH(2).CHO) is the most effective producer of ethylene in the model system and appears to be an intermediate in the reaction. 4. The evidence, from both tracer studies and from other precursors of ethylene in the reaction, indicates that ethylene is derived from the -CH(2).CH(2)- group of methionine.

Characterization of a single molecular QCA cell by Q-control enhanced amplitude modulation atomic force microscopy

Major technical challenges for reduction of device sizes for computation and memory are the interconnection and power dissipation problems. Molecular quantum-dot cellular automata (QCA) have been proposed as solutions to this problem. Silicon phthalocyanine (SiPc) is a possible candidate for a molecular QCA element. Therefore, it is important to develop an in situ observation technique to visualize individual SiPc molecules. We report here the first image of a single SiPc dimer in air by using quality factor control (Q-control) enhanced amplitude modulation atomic force microscopy (AFM) and an investigation of the interaction forces between the tip and SiPc dimer. The AFM was operated at 0% relative humidity in an ultrapure nitrogen environment either with or without Q-control. Theoretical simulations using the point-mass description of the AFM, demonstrated that Q-enhancement reduced the force exerted from the tip to the sample surface. Our results, consistent with theory, demonstrated that the image force was reduced and a greater height and a larger size were measured. The advantages of this method can be extended to the AFM observation of other "soft" structures, and these results can be useful for a wider community.

Adhesion enhancement of steel fibers to acrylic bone cement through a silane coupling agent

The use of a silane coupling agent (methacryloxypropyl-trichlorosilane) to improve the mechanical properties of steel fiber-reinforced acrylic bone cements was assessed. Changes to the tensile and fracture properties of bone cements reinforced with silane-coated or uncoated 316L stainless steel fibers of different aspect ratios were studied. Contact-angle measurements indicated that the coupling agent coats the metal surface through room temperature treatments in a short time (within 2 h). Push-out tests indicated that the interfacial shear strength of silane-coated 316L stainless steel rods is 141% higher than the uncoated rods. The elastic moduli, ultimate stresses, and fracture toughness of the silane-coated, steel fiber-reinforced bone cements are significantly higher than the bone cements reinforced with uncoated steel fibers. There were no differences in the tensile mechanical properties of the silane-coated or uncoated, steel fiber-reinforced cements after aging in a physiological saline solution, indicating that the bonding effectiveness is decreased by the intrusion of water at the metal-polymer interface. Because of possible biocompatibility issues with leaching of the silane coupling agent and no long-term mechanical benefit in simulated aging experiments, the use of these agents is not recommended for in vivo use.

Interpersonal influence and disordered eating behaviors in adolescent girls: the role of peer modeling, social reinforcement, and body-related teasing

This study investigated the association between interpersonal relationships, eating behaviors, and body esteem in a sample of adolescent girls. Participants included 876 girls who completed questionnaires regarding body esteem, eating behavior, peer pressure, and interpersonal relationships. Peer pressure was a strong predictor of eating behavior and body esteem after controlling for interpersonal variables. High externalized self-perceptions, self-reported teasing, and attributions about the importance of weight and shape for popularity and dating were important predictors of both body esteem and eating behavior. Also, girls who were nominated as popular by peers were more likely to engage in disordered eating and have lower body esteem. Results highlight the need for eating disorder prevention at the level of the peer group. Programs should focus on decreasing pressure to be thin, acceptance by peers for attributes other than appearance, and combating weight- and shape-related teasing within the school system.

Scanning tunneling microscopy and spectroscopy investigations of QCA molecules

Quantum-dot cellular automata (QCA), a computation paradigm based on the Coulomb interactions between neighboring cells. The key idea is to represent binary information, not by the state of a current switch (transistor), but rather by the configuration of charge in a bistable cell. In its molecular realization, the QCA cell can be a single molecule. QCA is ideally suited for molecular implementation since it exploits the molecule's ability to contain charge, and does not rely on any current flow between the molecules. We have examined using an UHV-STM some of the QCA molecules like silicon phthalocyanines and Fe-Ru complexes on Au (111) and Si (111) surfaces, which are suitable candidates for the molecular QCA approach.

Synthesis and properties of [Ru(2)(acac)(4)(bptz)](n+) (n=0,1) and crystal structure of [Ru(2)(acac)(4)(bptz)]

The neutral complex [Ru(2)(acac)(4)(bptz)] (I) has been prepared by the reaction of Ru(acac)(2)(CH(3)CN)(2) with bptz (bptz = 3,6-bis(2-pyridyl)-1,2,4,5-tetrazine) in acetone. The diruthenium(II,II) complex (I) is green and exhibits an intense metal-ligand charge-transfer band at 700 nm. Complex I is diamagnetic and has been characterized by NMR, optical spectroscopy, IR, and single-crystal X-ray diffraction. Crystal structure data for I are as follows: triclinic, P1, a = 11.709(2) A, b = 13.487(3) A, c = 15.151(3) A, alpha = 65.701(14) degrees, beta = 70.610(14) degrees, gamma = 75.50(2) degrees, V = 2038.8(6) A(3), Z = 2, R = 0.0610, for 4397 reflections with F(o) > 4sigmaF(o). Complex I shows reversible Ru(2)(II,II)-Ru(2)(II,III) and Ru(2)(II,III)-Ru(2)(III,III) couples at 0.17 and 0.97 V, respectively; the 800 mV separation indicates considerable stabilization of the mixed-valence species (K(com) > 10(13)). The diruthenium(II,III) complex, [Ru(2)(acac)(4)(bptz)](PF(6)) (II) is prepared quantitatively by one-electron oxidation of I with cerium(IV) ammonium nitrate in methanol followed by precipitation with NH(4)PF(6). Complex II is blue and shows an intense MLCT band at 575 nm and a weak band at 1220 nm in CHCl(3), which is assigned as the intervalence CT band. The mixed valence complex is paramagnetic, and an isotropic EPR signal at g = 2.17 is observed at 77 and 4 K. The solvent independence and narrowness of the 1200 nm band show that complex II is a Robin and Day class III mixed-valence complex.

Tightness of dental contact points in spaced and non-spaced permanent dentitions

One of the characteristics of normal occlusion is tight dental contact points (CPs). However, the magnitude and distribution of the tightness of a dental contact point (TDCP) in non-spaced versus spaced dentitions are unknown, as well as the mechanism controlling this arrangement. Two hypotheses were examined: the compression theory, i.e. the teeth touch each other in a compressive state; and the resistance theory, i.e. size and number of roots determine TDCP values. For the study, 60 subjects (27 men, 33 women), mean age 25 +/- 4.3 years, with a complete permanent dentition and no missing teeth were divided into spaced (n = 22) and non-spaced dentitions (n = 38). For each CP, four repeated measurements of peak strain were performed with a one-month interval. No significant differences were found between repeated measurements. All CPs demonstrated a continuous decreased TDCP in the postero-anterior direction. Consequently, in non-spaced dentitions TDCPs between molars were 100 per cent higher than incisors. The five anterior CPs of each jaw demonstrated similar TDCP values. Maxillary TDCPs versus mandibular antagonists were not significant. Mandibular TDCPs were significantly higher in men than in women (14 per cent). Anterior TDCPs were less in spaced than in non-spaced dentitions (55 per cent). Posterior TDCPs were also lower in spaced dentitions, however, to a lesser extent (25 per cent). With the exception of TDCPnon-spaced > TDCPspaced, which is partially explained by the compression theory, most of the findings support the resistance theory regulating TDCP characteristics of the permanent dentition.

Different physiological mechanisms control isovolumetric regulation and regulatory volume decrease in chick embryo cardiomyocytes

Cultured chick embryo cardiac myocytes submitted to a 180 mOsm/kg hyposmotic solution swell present a regulatory volume decrease (RVD). This RVD is mediated by a Ca(2+)influx followed by a 40% loss of total taurine content accompanied by the loss of lesser amounts of other osmolytes. Kidney cells respond to a gradual change in osmolality by maintaining their volume at the initial level. This is termed isovolumetric regulation (IVR), which may activate regulatory processes other than those observed with sudden changes in osmolality. When cardiac myocytes were exposed to a gradual change in osmolality, they show a partial IVR which is not dependent upon extracellular Ca(2+). Potassium channel blockers, quinidine and Ba(2+), and the chloride channel blocker, diphenylamine-2-carboxylate (DPC), compromise IVR in our model. Tritiated taurine loss and total intracellular K(+)contents were analyzed in cultured cardiomyocytes submitted to a gradual change in osmolality. The cultured cells lost approximately 10% of their taurine and 35% of their total K(+). These findings suggest that different compensatory mechanisms are activated when cells are exposed to stepwise and gradual changes in osmolality. Inorganic osmolytes (through conductive pathways) are preferentially mobilized during the physiological and/or patho-physiological IVR situation, perhaps reflecting energetic conservation in response to a less traumatic event for the cardiac myocytes.

Rescuing the N-cadherin knockout by cardiac-specific expression of N- or E-cadherin

Cell-cell adhesion mediated by some members of the cadherin family is essential for embryonic survival. The N-cadherin-null embryo dies during mid-gestation, with multiple developmental defects. We show that N-cadherin-null embryos expressing cadherins using muscle-specific promoters, alpha- or beta-myosin heavy chain, are partially rescued. Somewhat surprisingly, either N-cadherin or E-cadherin was effective in rescuing the embryos. The rescued embryos exhibited an increased number of somites, branchial arches and the presence of forelimb buds; however, in contrast, brain development was severely impaired. In rescued animals, the aberrant yolk sac morphology seen in N-cadherin-null embryos was corrected, demonstrating that this phenotype was secondary to the cardiac defect. Dye injection studies and analysis of chimeric animals that have both wild-type and N-cadherin-null cells support the conclusion that obstruction of the cardiac outflow tract represents a major defect that is likely to be the primary cause of pericardial swelling seen in null embryos. Although rescued embryos were more developed than null embryos, they were smaller than wild-type embryos, even though the integrity of the cardiovascular system appeared normal. The smaller size of rescued embryos may be due, at least in part, to increased apoptosis observed in tissues not rescued by transgene expression, indicating that N-cadherin-mediated cell adhesion provides an essential survival signal for embryonic cells. Our data provide in vivo evidence that cadherin adhesion is essential for cell survival and for normal heart development. Our data also show that E-cadherin can functionally substitute for N-cadherin during cardiogenesis, suggesting a critical role for cadherin-mediated cell-cell adhesion, but not cadherin family member-specific signaling, at the looping stage of heart development.

Na+/K+-ATPase inhibition during cardiac myocyte swelling: involvement of intracellular pH and Ca2+

Previous studies in chick embryo cardiac myocytes have shown that the inhibition of Na+/K+-ATPase with ouabain induces cell shrinkage in an isosmotic environment (290 mOsm). The same inhibition produces an enhanced RVD (regulatory volume decrease) in hyposmotic conditions (100 mOsm). It is also known that submitting chick embryo cardiomyocytes to a hyperosmotic solution induces shrinkage and a concurrent intracellular alkalization. The objective of this study was to evaluate the involvement of intracellular pH (pHi), intracellular Ca2+ ([Ca2+]i) and Na+/K+-ATPase inhibition during hyposmotic swelling. Changes in intracellular pH and Ca2+ were monitored using BCECF and fura-2, respectively. The addition of ouabain (100 microM) under both isosmotic and hyposmotic stimuli resulted in a large increase in [Ca2+]i (200%). A decrease in pHi (from 7.3 +/- 0.09 to 6.4 +/- 0.08, n = 6; p < 0.05) was only observed when ouabain was applied during hyposmotic swelling. This acidification was prevented by the removal of extracellular Ca2+. Inhibition of Na+/H+ exchange with amiloride (1 mM) had no effect on the ouabain-induced acidification. Preventing the mitochondrial accumulation of Ca2+ using CCCP (10 microM) resulted in a blockade of the progressive acidification normally induced by ouabain. The inhibition of mitochondrial membrane K+/H+ exchange with DCCD (1 mM) also completely prevented the acidification. Our results suggest that intracellular acidification upon cell swelling is mediated by an initial Ca2+ influx via Na+/Ca2+ exchange, which under hyposmotic conditions activates the K+ and Ca2+ mitochondrial exchange systems (K+/H+ and Ca2+/H+).

Cytoskeletal involvement during hypo-osmotic swelling and volume regulation in cultured chick cardiac myocytes

The membrane skeleton in spherical cardiac myocytes subjected to hypo-osmotic challenge was examined by laser scanning confocal microscopy. A distinct cortical layer intimately localized under the plasmalemma was revealed for spectrin and actin (including filamentous actin and alpha-sarcomeric actin). Desmin filaments were abundant and in close contact with the plasmalemma. During swelling and subsequent regulatory volume decrease (RVD) the structural integrity of these cytoskeletal elements remained intact, and the close association between actin and plasmalemma persisted as confirmed by double immunolabeling. Subplasmalemmal beta-tubulin labeling was sparse. Hypo-osmotic conditions disrupted the microtubules and depolymerized tubulin. Neither pretreatment with taxol nor with colchicine, resulted in any effect on cell volume regulation. The present results show that actin, desmin, and spectrin contribute to a subplasmalemmal cytoskeletal network in spherical cardiac myocytes, and that this membrane skeleton remains structurally intact during swelling and RVD. It is suggested that the integrity of this membrane skeleton is important for stabilization of the plasmalemma and the membrane-integrated proteins during hypo-osmotic challenge, and that it may participate in the regulation of the cell volume.

Postnatal lethality of P-cadherin/desmoglein 3 double knockout mice: demonstration of a cooperative effect of these cell adhesion molecules in tissue homeostasis of stratified squamous epithelia

To investigate the cooperativity of different cell adhesion molecules in maintaining the structural integrity of the epidermis, we have generated mice deficient for both a classical cadherin, P-cadherin, and a desmosomal cadherin, desmoglein 3. In epithelial cells, P-cadherin is localized to the adherens junction, whereas desmoglein 3 is found in desmosomes. Previous studies have shown that these two junctional complexes are important for keratinocyte cell-cell adhesion. Both P-cadherin and desmoglein 3 expression are restricted to the basal and most immediate suprabasal cells of the epidermis, whereas both proteins are found throughout the oral mucosal epithelium. Although P-cadherin mutant mice have no apparent defect in epithelial cell adhesion, the desmoglein 3 mutant phenotype resembles that of patients with the autoimmune disease pemphigus vulgaris, in that the mice develop spontaneous mucous membrane blisters and trauma-induced skin blisters. The oral lesions in DSG3-/- mice reduce their food intake, resulting in a runted phenotype; however, most animals recover and live past weaning age. In contrast, animals mutant for both P-cadherin and desmoglein 3 die before weaning. The majority of the double mutant animals die around 1 wk after birth, apparently due to malnutrition. These studies suggest that loss of P-cadherin leads to a more severe desmoglein 3 mutant phenotype in the double knockout mice. This is the first in vivo evidence of possible synergism between a classical and desmosomal cadherin.

Permeabilization by streptolysin-o reveals a role for calcium-dependent protein kinase c isoforms alpha and beta in the response of cultured cardiomyocytes to hyposmotic challenge

Immunocytochemical techniques indicate that the uninhibited activity of protein kinase C alpha and protein kinase C beta are necessary for a normal regulatory volume decrease (RVD) response of cultured chick embryo cardiomyocytes subjected to a hyposmotic environment. Antibodies against protein kinase C isoforms alpha, beta, gamma and epsilon were introduced into the cultured myocytes using a developed streptolysin-O (SLO) permeabilization technique that allows the targeted cells to accumulate large biomolecules without perturbing their normal physiological state. The loaded cells were then tested for their ability to RVD when submitted to hypo-osmotic stimulus. Results show that exposing the cultured cells to SLO in the presence of antibodies against protein kinase C alpha and beta, prior to volume challenge, significantly slows the RVD rate. Additional experiments that combined anti-alpha and anti-beta antibodies in the same exposure media did not result in a significantly different rate than the anti-alpha or anti-beta rates alone. The evidence gained in this study is in agreement with previous work in the cultured chick embryo cardiomyocyte that report the involvement of a calcium dependent protein kinase C in the signal transduction pathway of the RVD.

Comparisons of different stages of chick embryonic development by the physiological regulatory response to hyposmotic challenge

Cardiac myocytes isolated and cultured from 11 day chick embryos present a Ca(2+)-dependent regulatory volume decrease (RVD) when exposed to hyposmotic stimulus. The RVD of myocytes from different embryonic stages were analyzed to evaluate their physiological performance through development. Among the several embryonic stages analyzed (6, 11, 16 and 19 days) only 19 day cardiac myocytes present a greater RVD when compared with 11 day (considered as control), the other ages showed no difference in the regulatory response. As it is known that RVD is Ca(2+) dependent, we decided to investigate the transient free Ca(2+) response during the hyposmotic swelling of the 11 and 19 day stages. The 11 day cardiac myocyte showed a transient 40% increase in intracellular free Ca(2+) when submitted to hyposmotic solutions, and the free Ca(2+) returned to baseline levels while the cells remained in hyposmotic buffer. However, the intracellular free Ca(2+) transient in the 19 day cells during hyposmotic challenge increases 100% and instead of returning to baseline levels, declines to 55% above control, well after the 11 day transient has returned to baseline. Also, quantitative fluorescence microscopy revealed that 19 day cardiac myocytes have more sarcoplasmic reticulum (SR) Ca(2+) ATPase sites per cell as compared to the 11 day cells. Our findings suggest that 19 day cells have more developed intracellular Ca(2+) stores (SR). By evoking the mechanism of Ca(2+) induced Ca(2+) release, the cells have more free Ca(2+) available for signaling the RVD during hyposmotic swelling.

Membrane skeleton in cultured chick cardiac myocytes revealed by high resolution immunocytochemistry

Distribution of cytoskeletal proteins with emphasis on the membrane-cytoskeleton interface was examined in cultured cardiac myocytes. Using specific antibodies recognizing alpha-sarcomeric actin, desmin, beta-tubulin, spectrin/alpha-fodrin and ankyrin, respectively, the cellular localization of these cytoskeletal proteins was detected by laser scanning confocal microscopy. In addition, the fine filamentous structure of these proteins was identified by combining silver-enhanced immunogold labelling with electron microscopy. The latter technique employed the sequence of quick-freezing, deep-etching and rotary shadowing of the specimens. Conventional transmission electron microscopy of the spherical cardiac myocytes revealed a filamentous submembranous layer, approximately 100 nm thick. Specific immunolabelling of alpha-sarcomeric actin and spectrin/alpha-fodrin as well as ankyrin was seen beneath the plasmalemma. A three-dimensional meshwork of spectrin/alpha-fodrin was shown. Numerous desmin filaments that exhibited a tortuous course throughout the cells were also observed running in parallel with the surface in the submembranous area, whereas beta-tubulin was infrequently detected in these areas. In conclusion, the present study shows that spherical cardiac myocytes contain a distinct and complex three-dimensional membrane skeleton. Major constituents of this distinct submembranous layer were spectrin/alpha-fodrin fibres as well as actin and desmin filaments.

Estrogen replacement therapy and cognitive decline in memory-impaired post-menopausal women

BACKGROUND

Estrogen replacement therapy (ERT) may delay dementia-related cognitive decline in post-menopausal women, but few studies have longitudinally examined this relationship and none has controlled for baseline functioning or concurrent medication.

METHODS

We report the results of a 1-year retrospective longitudinal study examining cognitive functioning in female estrogen and nonestrogen users (n = 3128) who presented to the state of California memory disorder clinics in a naturalistic multisite study of senile dementia, Alzheimer's type (SDAT), and other cognitive impairments.

RESULTS

At baseline, estrogen users had significantly lower rates of SDAT diagnoses (possible and probable) than nonestrogen users, and significantly higher rates of the lesser diagnoses of "cognitive impairment" and "no dementia." ERT was significantly associated with higher cognitive functioning at baseline and at 1 year follow-up (n = 358). Nonestrogen users deteriorated significantly from baseline to follow-up; estrogen users did not. Results were similar in groups matched on baseline Blessed-Roth Dementia Rating Scale (BRDRS) ratings (n = 32) and in a variety of subpopulations.

CONCLUSIONS

These findings are consistent with estrogen acting as a protective factor against cognitive deterioration in post-menopausal women with SDAT and other cognitive impairments, and may suggest an increased effect in earlier stages of cognitive impairment.

Field stimulation of isolated chick heart cells: comparison of experimental and theoretical activation thresholds

INTRODUCTION

This study examines the accuracy of using membrane models to predict activation thresholds for chick heart cells during field stimulation.

METHODS AND RESULTS

Activation thresholds were measured experimentally in ten embryonic chick heart cells at 37 degrees C for stimulus durations 0.2 to 40 msec. Activation was assessed by observing the mechanical twitch of the cell. The heart cells ranged in diameter from 15.0 to 26.7 microm. Since the electric field required for activation depends on diameter, the thresholds were expressed as the maximum field-induced transmembrane potential, Vth = 1.5 a Eth, where a is the cell radius and Eth is the strength of the electric field at threshold. A cell model was created using a singular perturbation method and membrane models describing the ionic currents of a heart cell. The study used membrane models of Ebihara and Johnson (1980), Luo and Rudy (1991), Shrier and Clay (1994), and their combinations. The results show that for stimuli longer than 1 msec, theoretical activation thresholds were within one standard deviation of experimental thresholds. For shorter stimuli, the models failed to predict thresholds because of a premature deactivation of the sodium current. The modification of the m gates dynamics, so that they closed with a time constant of 1.4 msec, allowed to predict thresholds for all durations. The root mean square error between experimental and theoretical thresholds was 6.14%.

CONCLUSIONS

The existing membrane models can predict thresholds for field stimulation only for stimuli longer than 1 msec. For shorter stimuli, the models need a more accurate representation of the sodium tail current.

Developmental patterns in security of attachment to mother and father in late childhood and early adolescence: associations with peer relations

This study examined developmental differences in two dimensions of attachment security (parental availability and child dependency on parents) in late childhood (N = 274) and early adolescence (N = 267) and their association with peer relations. Children's perceptions of mother's availability and boys' perceptions of father's availability did not differ as a function of age. Dependency on parents, however, decreased with age. Findings highlight the importance of distinguishing between parental availability and reliance on parental help when measuring attachment developmentally. Children's reports of positive friendship qualities and lack of conflict in their best friendships were related to attachment to both mother and father, whereas the presence of a reciprocated friendship and popularity were not. Father availability was a particularly important predictor of lower conflict with best friends. Findings indicate that the quality of parent-child attachment generalizes primarily to the quality of children's close peer relations.

The dentition of Abraham's people. Why Abraham left Mesopotamia

Ancient Mesopotamia (southern Iraq) in 2000 B.C. was the home of the biblical figure Abraham and his people. An analysis of skeletal material from cemeteries in the ancient cities of Ur (birthplace of Abraham) and Kish shows a homogeneous, short-lived population that suffered severe dental attrition (95 percent of inhabitants), periodontal disease (42 percent) and caries (two percent). Many oral congenital and neoplastic lesions were noted Skeletal (dental) evidence indicates the population suffered from extensive disease and nutritional deficiency. Of special note was a possible case of endodontic treatment. The people of Abraham had modern dentition but relatively poor dental health. It is probable that Abraham, if in truth he existed, left Mesopotamia because of the threat of famine, as evidenced by biblical record, geologic strata and dental analysis.

Antigen-specific antibody responses in lupus patients following immunization

OBJECTIVE

To determine the safety and efficacy of 3 clinically relevant vaccines in patients with systemic lupus erythematosus (SLE).

METHODS

We studied 73 consecutive SLE patients immunized with pneumococcal, tetanus toxoid (TT), and Haemophilus influenzae type B (HIB) vaccines. Patients were evaluated preimmunization and 12 weeks postimmunization for disease activity and immunization side effects.

RESULTS

Eighty-four percent of the SLE patients developed a 4-fold titer increase in response to at least 1 vaccine, with 51% developing a 2-fold titer increase with all 3 vaccines. The majority of SLE patients developed protective levels of antibody to TT (90%) and HIB (88%). Although protective antibody levels could not be determined for pneumococcus, almost half of the patients (47%) developed a 4-fold antibody response. There was a trend toward a lower antibody response in patients with active disease treated with immunosuppressive therapy. Overall lupus disease activity was unaffected by immunization.

CONCLUSION

Immunization is safe in SLE patients, with the overwhelming majority developing protective antibody levels. Therefore, SLE patients should receive immunizations according to the recommendations of the Centers for Disease Control and Prevention and the Immunization Practices Advisory Committee.

Rapid palatal expansion. Part 3: strains developed during active and retention phases

Patterns of strain accumulation/dissipation during the active and retention phases of rapid palatal expansion treatment were studied in a preliminary animal model (5 cats) followed by clinical study (14 patients). Two uni-axial strain gauges were bonded to the arms of a hyrax screw. The strain gauges were wired intraorally to a common male connector and protected against salivary assault. For strain registration, the connector was hooked to a switch and balance instrument and a digital strain indicator. The screw was activated (4 x 1/4 turn) every 3 to 4 days and strain and interarch distances were measured during rapid palatal expansion active and retention phases. Interarch distances were also measured during the relapse phase. Both studies share the same results. Strains and expansion increased progressively during active and retention phases of rapid palatal expansion. No difference between anterior and posterior strain was found. An immediate dental strain response that occurred during screw activations (intrasession strain) was related to tooth compression in the PDL. During the 3 to 4 day pause, a delayed skeletal strain response (intersession strain) developed that was inverted or continuous to the preceding intrasession strain. Complete dissipation of residual strains was limited to the first 1 to 3 active phase sessions. Strain accretion resulted essentially from intersession strain build-up. Strain level was preserved during the retention phase, apparently due to relapse strains. Relapse strains could not be measured but are inferred from the predominant interarch rebound measured during the relapse phase. Clinically, an extension of the intersession intervals and the retention phase are recommended.

Rapid palatal expansion. Part 2: Dentoskeletal changes in cats with patent versus synostosed midpalatal suture

Intercanine expansion (C-C) following rapid palatal expansion is made up of sutural displacement (Sd-Sd), tooth tip (Tt-Tt), tooth displacement (Td-Td), and alveolar process tipping and bending (At+b-At+b). The involvement of these four components was studied on 10 rapid palatal expansion treated and two control cats during an active phase (25 days), a retention phase (60 days), and a relapse phase (60 days). The midpalatal suture was analyzed for linear measurements, radiopaque versus radiolucent zones and optical density from occlusal radiographs. Nine treated cats exhibited sutural split and one treated cat showed no split as a result of synostosis of the suture. The contribution of the four constituents [(Sd-Sd):(Tt-Tt):(Td-Td):(At+b-At+b)] to the C-C expansion changed from active to relapse phase from [45%:15%:25%:15%] to [50%:25%:25%:0%] in the animals with sutural split and from [0%:40%:60%:0%] to [0%:0%:100%:0%] in the cat without sutural split, implying the major role of sutural displacement in patent suture, and tooth displacement in synostosed suture. The latter indicates the potential buccal corticalis fenestration, dehiscence or perforation in synostosed suture undergoing RPE. In patent suture (animals with sutural split), optical density increased during rapid palatal expansion (soft tissue build-up) and decreased during retention (remineralization) and relapse phases (medial convergence of the palatal processes). In the animal without sutural split, a continuous decrease in the optical density (predetermined ossification) was found. The progressive six-fold surge in coefficient of variation of C-C expansion during the relapse phase indicates limitation in predicting rapid palatal expansion stability. Clinically, the use of serial occlusal radiographs during rapid palatal expansion is recommended to evaluate patency and extent of retention period.