Manipulating magnetic and magnetoresistive properties by oxygen vacancy complexes in GCMO thin films

The effect ofin situannealing is investigated in Gd_0.1Ca_0.9MnO₃(GCMO) thin films in oxygen and vacuum atmospheres. We show that the reduction of oxygen content in GCMO lattice by vacuum annealing induced more oxygen complex vacancies in both subsurface and interface regions and larger grain domains when compared with the pristine one. Consequently, the double exchange interaction is suppressed and the metallic-ferromagnetic state below Curie temperature turned into spin-glass insulating state. In contrast, the magnetic and resistivity measurements show that the oxygen treatment increases ferromagnetic phase volume, resulting in greater magnetization (M_S) and improved magnetoresistivity properties below Curie temperature by improving the double exchange interaction. The threshold field to observe the training effect is decreased in oxygen treated film. In addition, the positron annihilation spectroscopy analysis exhibits fewer open volume defects in the subsurface region for oxygen treated film when compared with the pristine sample. These results unambiguously demonstrate that the oxygen treated film with significant spin memory and greater magnetoresistance can be a potential candidate for the future memristor applications.

Tuned AFM-FM coupling by the formation of vacancy complex in Gd0.6Ca0.4MnO3thin film lattice

The effect ofin situoxygen and vacuum annealings on the low bandwidth manganite Gd_1-xCa_xMnO₃(GCMO) thin film withx= 0.4 was investigated. Based on the magnetic measurements, the AFM-FM coupling is suppressed by the vacuum annealing treatment via destroying the double exchange interaction and increasing the unit cell volume by converting the Mn⁴⁺to the Mn³⁺. Consequently, resistance increases significantly compared to pristine film. The results are explained by a model obtained from the positron annihilation studies, where the vacuum annealing increased the annihilation lifetime in A and B sites due to the formation of vacancy complexesV_A,B-V_O, which was not the case in the pristine sample. The positron annihilation analysis indicated that most of the open volume defects have been detected in the interface region rather than on the subsurface layer and this result is confirmed by detailed x-ray reflection analysis. On the other hand, the effect of oxygen annealing on the unit cell volume and magnetization was insignificant. This is in agreement with positron annihilation results which demonstrated that the introduction of oxygen does not change the number of cation vacancies significantly. This work demonstrates that the modification of oxygen vacancies and vacancy complexes can tune magnetic and electronic structure of the epitaxial thin films to provide new functionalities in future applications.

Metastable ferromagnetic flux closure-type domains in strain relaxed Gd0.1Ca0.9MnO3thin films

We have systematically studied the structural, electrical transport, and magnetic properties of Gd_0.1Ca_0.9MnO₃thin films in function of thickness, which ranged from 22 nm up to 220 nm. We have found that, although no strong substrate-induced strain was detected for any thickness, a sudden change in the electric transport properties was observed when the film thickness increases above 80 nm. While thinner samples are insulating in the whole temperature range, the samples thicker than 80 nm show a clear insulator-to-metal transition (IMT) at around 100 K. The IMT coincides with the appearance of a ferromagnetic phase that is absent in the thinner samples. We associate this change in behavior with a critical film thickness that induces a sudden change in domain configuration, from in-plane domain to a closed flux-type domain with out-of-plane orientations. These out-of-plane oriented domains are meta-stable ferromagnetic in nature and result in an IMT which is accompanied by a hysteretic magnetoresistance behavior.

A Pilot Study of the Impact of Microwave Ablation on the Dielectric Properties of Breast Tissue

Percutaneous microwave ablation (MWA) is a promising technology for patients with breast cancer, as it may help treat individuals who have less aggressive cancers or do not respond to targeted therapies in the neoadjuvant or pre-surgical setting. In this study, we investigate changes to the microwave dielectric properties of breast tissue that are induced by MWA. While similar changes have been characterized for relatively homogeneous tissues, such as liver, those prior results are not directly translatable to breast tissue because of the extreme tissue heterogeneity present in the breast. This study was motivated, in part by the expectation that the changes in the dielectric properties of the microwave antenna’s operation environment will be impacted by tissue composition of the ablation target, which includes not only the tumor, but also its margins. Accordingly, this target comprises a heterogeneous mix of malignant, healthy glandular, and adipose tissue. Therefore, knowledge of MWA impact on breast dielectric properties is essential for the successful development of MWA systems for breast cancer. We performed ablations in 14 human ex-vivo prophylactic mastectomy specimens from surgeries that were conducted at the UW Hospital and monitored the temperature in the vicinity of the MWA antenna during ablation. After ablation we measured the dielectric properties of the tissue and analyzed the tissue samples to determine both the tissue composition and the extent of damage due to the ablation. We observed that MWA induced cell damage across all tissue compositions, and found that the microwave frequency-dependent relative permittivity and conductivity of damaged tissue are lower than those of healthy tissue, especially for tissue with high fibroglandular content. The results provide information for future developments on breast MWA systems.

Quantitative assessment of distant recurrence risk in early stage breast cancer using a nonlinear combination of pathological, clinical and imaging variables

Use of genomic assays to determine distant recurrence risk in patients with early stage breast cancer has expanded and is now included in the American Joint Committee on Cancer staging manual. Algorithmic alternatives using standard clinical and pathology information may provide equivalent benefit in settings where genomic tests, such as OncotypeDx, are unavailable. We developed an artificial neural network (ANN) model to nonlinearly estimate risk of distant cancer recurrence. In addition to clinical and pathological variables, we enhanced our model using intraoperatively determined global mammographic breast density (MBD) and local breast density (LBD). LBD was measured with optical spectral imaging capable of sensing regional concentrations of tissue constituents. A cohort of 56 ER+ patients with an OncotypeDx score was evaluated. We demonstrated that combining MBD/LBD measurements with clinical and pathological variables improves distant recurrence risk prediction accuracy, with high correlation (r = 0.98) to the OncotypeDx recurrence score.

The Sigma-2 Receptor and Progesterone Receptor Membrane Component 1 are Different Binding Sites Derived From Independent Genes

The sigma-2 receptor (S2R) is a potential therapeutic target for cancer and neuronal diseases. However, the identity of the S2R has remained a matter of debate. Historically, the S2R has been defined as (1) a binding site with high affinity to 1,3-di-o-tolylguanidine (DTG) and haloperidol but not to the selective sigma-1 receptor ligand (+)-pentazocine, and (2) a protein of 18–21 kDa, as shown by specific photolabeling with [³H]-Azido-DTG and [¹²⁵I]-iodoazido-fenpropimorph ([¹²⁵I]-IAF). Recently, the progesterone receptor membrane component 1 (PGRMC1), a 25 kDa protein, was reported to be the S2R (Nature Communications, 2011, 2:380). To confirm this identification, we created PGRMC1 knockout NSC34 cell lines using the CRISPR/Cas9 technology. We found that in NSC34 cells devoid of or overexpressing PGRMC1, the maximum [³H]-DTG binding to the S2R (B_max) as well as the DTG-protectable [¹²⁵I]-IAF photolabeling of the S2R were similar to those of wild-type control cells. Furthermore, the affinities of DTG and haloperidol for PGRMC1 (K_I = 472 μM and 350 μM, respectively), as determined in competition with [³H]-progesterone, were more than 3 orders of magnitude lower than those reported for the S2R (20–80 nM). These results clarify that PGRMC1 and the S2R are distinct binding sites expressed by different genes.

•

The sigma-2 receptor is an important drug target but its molecular identity has remained a hot topic of debate.

•

PGRMC1 has recently been reported to be the sigma-2 binding site (Nature Communications, 2011, 2:380).

•

Our data clarify that PGRMC1 and the sigma-2 receptor are distinct binding sites expressed by different genes.

The sigma-2 receptor (S2R) is a potential important therapeutic target for cancer and neuronal diseases, yet its gene identity is a long-held mystery. While a recent prominent report concluded that a progesterone-binding protein (PGRMC1) is the sigma-2 receptor, the critical defining evidence was missing. We re-tested this conclusion using a genome-editing technology combined with chemical biology and pharmacological determinations. The unambiguous results indicate that PGRMC1 is not the originally defined true sigma-2 receptor. This study may benefit public health by guiding future discovery of the true identity of the sigma-2 drug binding site.

Integrating cereal genomics to support innovation in the Triticeae

The genomic resources of small grain cereals that include some of the most important crop species such as wheat, barley, and rye are attaining a level of completion that now is contributing to new structural and functional studies as well as refining molecular marker development and mapping strategies for increasing the efficiency of breeding processes. The integration of new efforts to obtain reference sequences in bread wheat and barley, in particular, is accelerating the acquisition and interpretation of genome-level analyses in both of these major crops.

Integrating cereal genomics to support innovation in the Triticeae

The genomic resources of small grain cereals that include some of the most important crop species such as wheat, barley, and rye are attaining a level of completion that now is contributing to new structural and functional studies as well as refining molecular marker development and mapping strategies for increasing the efficiency of breeding processes. The integration of new efforts to obtain reference sequences in bread wheat and barley, in particular, is accelerating the acquisition and interpretation of genome-level analyses in both of these major crops.

Mapping of major spot-type and net-type net-blotch resistance genes in the Ethiopian barley line CI 9819

Net blotch of barley ( Hordeum vulgare L.), caused by the fungal phytopathogen Pyrenophora teres Drechs. f. teres Smedeg., constitutes one of the most serious constraints to barley production worldwide. Two forms of the disease, the net form, caused by P. teres f. teres, and the spot form, caused by P. teres f. maculata, are differentiated by the type of symptoms on leaves. Several barley lines with major gene resistance to net blotch have been identified. Earlier, one of these was mapped in the Rolfi × CI 9819 cross to barley chromosome 6H, using a mixture of 4 Finnish isolates of P. teres f. teres. In this study, we used the same barley progeny to map resistance to 4 spot-type isolates and 4 net-type isolates of P. teres. With all net-type isolates, a major resistance gene was located on chromosome 6H, in the same position as described previously, explaining up to 88% of the phenotypic variation in infection response in the progeny. We designate this gene Rpt5. Several minor resistance genes were located on chromosomes 1H, 2H, 3H, 5H, and 7H. These minor genes were not genuinely isolate-specific, but their effect varied among isolates and experiments. When the spot-type isolates were used for infection, a major isolate-specific resistance gene was located on chromosome 5H, close to microsatellite marker HVLEU, explaining up to 84% of the phenotypic variation in infection response in the progeny. We designate this gene Rpt6. No minor gene effects were detected in spot-type isolates. The Ethiopian 2-rowed barley line CI 9819 thus carries at least 2 independent major genes for net-blotch resistance: Rpt5, active against net-type isolates; and Rpt6, active against specific spot-type isolates.

Shear bond strength of six restorative materials

The purpose of this study was to determine and compare the shear bond strength of a conventional glass-ionomer cement, a resin modified glass-ionomer, a composite resin and three compomer restorative materials. Dentin of the occlusal surfaces from sixty extracted human permanent molars were prepared for shear bond strength testing. The specimens were randomly divided into six groups of 10 each. Dentinal surfaces were treated according to the instructions of manufacturers for each material. Each restorative material was placed inside nylon cylinders 2 mm high with an internal diameter of 3 mm, which were placed perpendicular to dentin surfaces. Shear bond strengths were determined using an Universal Testing Machine at crosshead speed of 0.5 mm/min in a compression mode. Conventional glass-ionomer, Ketac-Molar aplicap showed the lowest mean shear bond strength 3.77+/-1.76 (X +/- SD MPa) and the composite resin, Heliomolar showed the highest mean shear bond strength 16.54+/-1.65 while the mean bond strength of Fuji II LC was 9.55+/-1.06. The shear bond strengths of compomer restorative materials were 12.83+/-1.42, 10.64+/-1.42 and 11.19+/-1.19 for Compoglass, Hytac and Dyract respectively. ANOVA revealed statistically significant differences in the mean shear bond strengths of all groups (P<0.001). No statistically significant difference was found between the three compomer materials (P>0.5). Ketac-Molar and composite resin showed statistically significant difference (P<0.0005). The mode of fracture varied between materials. It is concluded that the compomer restorative materials show higher shear bond strength than conventional glass-ionomer and resin modified glass-ionomer, but less than composite resin. The fracture mode is not related to the shear bond strengths values.

Tumor development is retarded in mice lacking the gene for urokinase-type plasminogen activator or its inhibitor, plasminogen activator inhibitor-1

In vivo tumor progression in mice with targeted deficiencies in urokinase-type plasminogen activator (UPA-/-) and its inhibitor, plasminogen activator inhibitor-1 (PAI-1-/-), was studied using a fibrosarcoma tumor model. Murine T241 fibrosarcoma cells were s.c. implanted into three groups of mice with the following genotypes, wild-type (WT), UPA-/-, and PAI-1-/-. A significantly diminished primary tumor growth in UPA-/- and PAI-1-/- mice occurred, relative to WT mice. Tumors in UPA-/- and PAI-1-/- mice displayed lower proliferative and higher apoptotic indices and displayed a different neovascular morphology, as compared with WT mice. These results are consistent with the decreased growth rates of this tumor in these gene-deleted mice. Immunohistochemical analyses of the tumors revealed a decrease in vascularity and vascular endothelial growth factor expression only in tumors in PAI-1-/- mice. Analyses of the relative extents of corneal angiogenesis in these same animals, induced by basic fibroblast growth factor, corroborated the resistance of PAI-1-/- mice to neovascularization. The results obtained suggest that the host fibrinolytic system plays an important role in tumor growth in this model. Alterations in host expression of components of this system may alter tumor growth and dissemination by affecting the balance between tumor cell death and proliferation, as well as extracellular matrix changes needed for invasiveness and angiogenesis.

Torsional resistance of crowns cemented to composite cores involving three stainless steel endodontic post designs

STATEMENT OF PROBLEM

There are no studies analyzing the effects of a crown in relationship to torsional resistance for a titanium-reinforced core material supported by a post.

PURPOSE

This study investigated the effects of post design on the torsional resistance of a crown supported by a titanium-reinforced composite core material (Ti-Core) and 3 endodontic posts (AccessPost, Flexi-Post, and ParaPost).

MATERIAL AND METHOD

Three groups of 10 specimens per group were studied. A total of 30 recently extracted human single-rooted (incisors) teeth with their crowns removed were used. Post holes preparations were created according to manufacturer's instructions. All posts were cemented using Flexi-Flow with titanium cement. Scotchbond Multi-Purpose bonding system was used as the bonding system for all groups. All cores were fabricated with Ti-Core with titanium core material with hard copper bands as the matrix. The Ti-Core core material was allowed to set for 1 hour. Metal crowns were fabricated and cemented with zinc phosphate cement. Specimens were placed in a special jig and a clockwise torsional force was applied. Torsional force was measured on a Lebow 1102-200 torque transducer and recorded on a Hewlett Packard 7015B X-Y recorder in inch x ounce. A 1-way analysis of variance (ANOVA) was used to test for statistical significance (P < .001).

RESULTS

The torsional values (inch x ounce) were AccessPost 77.2 +/- 30.3, Flexi-Post 162.2 +/- 51.2, and ParaPost 60.9 +/- 28.4. SNK and Scheffé comparison tests revealed that the Flexi-Post group had significantly greater resistance to torque loading than the AccessPost and ParaPost groups, which were statistically similar to each other.

CONCLUSION

Post design has an effect on torsional resistance of a crown supported by titanium-reinforced core build-up and post. The threaded split-shank design of the Flexi-Post dowel offers significantly greater resistance to torsional loading than the passive posts studied.

Calpain inhibitors protect auditory sensory cells from hypoxia and neurotrophin-withdrawal induced apoptosis

Inhibitors of calpain have been shown to protect nerve growth factor (NGF)-deprived ciliary ganglion neurons and hypoxic cortical neurons. Calpains have been identified in the cochlea and are active during ischemic injury. Since apoptosis can be initiated by loss of neurotrophic support, hypoxia, and ototoxins (e.g., cisplatin, CDDP), the role of calpain inhibitors under these conditions was examined in auditory hair cells and neurons. Dissociated spiral ganglion neuron (SGN) cell cultures and organ of Corti explants from P3 rats were used to test the efficacy of calpain inhibitors as otoprotective molecules. Our results indicate that calpain inhibitor I, calpain inhibitor II, and leupeptin all provided significant protection of SGNs against neurotrophin-withdrawal and hypoxia-induced apoptosis. The increase in neuronal survival ranged from 2.16 to 2.31 times greater than in untreated neurotrophin-withdrawn SGN cell cultures. BOC-Asp(Ome)-Fluoromethyl Ketone (B-D-FMK), a general caspase inhibitor, increased neuronal survival 2.16 times more. Neuronal survival rates were from 1.88 to 2.27 times greater than in untreated, hypoxic neurons and hair cell survival rates were from 1.98 to 2.03 times greater than untreated, hypoxic organ of Corti explants. However, protection of auditory hair cells and neurons from CDDP-induced damage (10 and 6 micrograms/ml, respectively) was limited with any of these calpain inhibitors. Apoptotic pathways initiated by neurotrophin-deprivation and ototoxic stress (e.g., CDDP) have been shown to be different. Our results agree with this finding, with neurotrophin-withdrawal and hypoxia, but not CDDP damage-induced apoptosis being calpain-dependent.

Children on the move and vaccination coverage in a low-income, urban Latino population

OBJECTIVES

The purpose of this study was to determine the impact of childhood moves and foreign birth on vaccination coverage among Latino children in New York City.

METHODS

Vaccination coverage was assessed in a survey of 314 children younger than 5 years at 2 immunization clinics.

RESULTS

Forty-seven percent of the study children had moved abroad. After adjustment for health insurance, regular source of care, and country of birth, child moves had no independent effect on vaccination coverage. Foreign-born children had diphtheria-pertussis-tetanus, oral polio vaccine, and measles-mumps-rubella vaccination coverage rates similar to those of US-born children, but they were underimmunized in regard to Haemophilus influenzae type b and hepatitis B.

CONCLUSIONS

Foreign birth, but not childhood moves, is a barrier to vaccinations among low-income, urban Latino children.

Clinical evaluation of cell demodulated targeted electronic anesthesia

Electronic anesthesia is an effective adjunct for the management of dental pain, and has been used in medicine and dentistry for several decades. The purpose of this study was to evaluate the effectiveness of dental electronic anesthesia while preparing teeth for large restorations and full crown coverage. The single-blind study involved the use of two identical units (Cedeta Mk3). One was a fully operational, commercially available unit (active unit), while the other had been modified to prevent current from reaching the electrodes (control unit). Both the non-working control device and the active unit had a normally functioning indicator light that glowed when the unit was turned on. The study participants consisted of 100 patients selected from the roster at New York University College of Dentistry. Subjects were selected if (1) their prescribed treatment plans required large class I, II, III, IV, or V restorations or full coverage crowns, (2) they had previous treatment performed with the use of an injectable local anesthetic, and (3) their medical history showed a lack of medical contraindications. The active unit group had 31 subjects with large restorations required, 5 patients needing inlay/onlay preparations and 14 subjects requiring full coverage. The control unit group had 43 subjects needing large operative restorations, 1 onlay and 6 subjects needing full coverage. Each subject was informed that he/she would be able to eliminate the pain from the dental procedure by maintaining control of the electronic dental anesthesia unit (reaching a therapeutic level). If unmanageable discomfort occurred, intraligamentous local anesthesia would be administered. Two of the 50 subjects who received the control device were able to tolerate the dental procedure, the rest were given the rescue anesthetic upon request. Forty-three of the 50 subjects who received the active unit responded with an excellent or very good evaluation for pain control, with no rescue anesthetic required. Seventy-four dental procedures were performed on the 50 subjects who received the active unit. Forty-five of the subjects in the active unit group said they would prefer to have electronic anesthesia for their next dental treatment, rather than the novocaine they had previously experienced. Forty-eight of the subjects in the control unit group said that they would prefer the traditional novocaine injection for their next dental treatment.

Enhanced retention of glass-ionomer sealant by enamel etching: a microleakage and scanning electron microscopic study

OBJECTIVE

A microleakage study and a scanning electron microscopic investigation were conducted to test whether etching of enamel would improve adhesion of glass-ionomer cement sealants to fissure enamel.

METHOD AND MATERIALS

Forty-eight extracted human molars and premolars were divided into 2 equal groups, and their crowns were cleaned with pumice. In group 1 enamel was etched for 45 seconds with 37% phosphoric acid. In group 2, enamel was not etched. Glass-ionomer sealant was applied to all 48 teeth. Twenty teeth from each group were thermocycled in water (120 cycles between 0 degree C and 56 degrees C) and stained with 0.5% methylene blue solution. The remaining 4 teeth from each group served as a control for the scanning electron microscopic evaluation. Twelve teeth from each group were cut into 5 sections, and 12 were cleaved into 3 sections in a buccolingual direction.

RESULTS

Statistically significant differences in amounts of microleakage were found between group 1 and group 2. Minimal microleakage was detected in 90% of the etched teeth, whereas extensive microleakage was observed in 85% of nonetched teeth. The scanning electron microscopic evaluation correlated positively with the microleakage observations. The etched teeth revealed a cohesive failure within the sealant material, while the nonetched teeth demonstrated an adhesive failure at the sealant-enamel interface. Observation of the nonthermocycled teeth confirmed those findings.

CONCLUSION

Results suggested that etching prior to application enhances the bonding of glass-ionomer sealant to fissure enamel.

Clinical effectiveness of a Class V flowable composite resin system

This clinical study evaluated a Class V flowable composite resin restoration system and its ability to reduce dentin sensitivity. Twenty-one patients required Class V restorations because of erosion, abrasion, or decay at the cervical area. Each patient exhibited moderate or severe sensitivity and required replacement of tooth structure. The degree of sensitivity was determined by either tactile scraping of the tip of an explorer over the surface of the tooth or by an air blast from a syringe for 5 seconds. A total of 52 restorations were performed. According to phone conversations and questionnaires, 1 patient experienced continued sensitivity on 1 treated tooth for a duration of 1 week, but this sensitivity was gone at 1-month, 3-month, 6-month, and 1-year recalls. None of the other patients exhibited sensitivity at any phone checks or during recall visits.

Ultrasound appearances of intra- and extrahepatic biliary ascariasis

BACKGROUND

To determine the range of ultrasonographic (US) appearances of Ascaris lumbricoides roundworms in the biliary system, their distribution in the intra- and extrahepatic parts of the system, and associated features.

METHODS

All cases of biliary ascariasis during a 10-year period were reviewed. There were 42 cases in which diagnosis was based on established US criteria, and 2 cases diagnosed surgically in which US had been negative. These 44 cases occurred in 36 patients.

RESULTS

In the US-diagnosed cases, worms were present in intrahepatic ducts in 32 cases, in the main duct in 37, and in the gallbladder in eight. In six cases, the liver was lifted off the main portal vein by a bundle of worms obliterating the lumen of the main bile duct. Worms packing and dilating intrahepatic ducts produced pseudotumorous appearances in the liver in four cases and bundlelike appearances in three. Worms were also seen in the pancreatic duct in two cases. Stones in intrahepatic ducts were present in 12 patients.

CONCLUSION

Biliary ascariasis should be searched for inside and outside the liver. The appearances of bundles and boluses are different from those of single worms. Intra- and extrahepatic biliary stones may be present.

A review of all-ceramic restorations

To select the most appropriate type of all-ceramic system for clinical use, the clinician must be familiar with the differences between systems. This article discusses five categories of all-ceramic restorative systems relative to their processing techniques, strength and wear characteristics. The authors present and compare results of published in vitro studies and short-term clinical studies.

Bowel herniation through the torn diaphragm: I. Gastric herniation

Six cases of gastric herniation through the lacerated diaphragm are presented. Plain radiographs and single-contrast barium examinations demonstrate simple signs that either have not been previously published or need restatement. Some pitfalls that still delay diagnosis are also shown.

Bowel herniation through the torn diaphragm: II. Intestinal herniation

Five cases of intestinal herniation through the torn diaphragm are presented. Plain radiography, single-contrast examination, and ultrasonography show some simple features that either have not been previously published or need restatement. Some pitfalls that still delay diagnosis are also shown.

Comparison of fatigue for three prefabricated threaded post systems

Post designs may have a direct effect on fracture resistance of endodontically treated teeth. This in vitro study compared the resistance of three prefabricated threaded post systems with lateral shearing forces. After endodontics were completed, prefabricated posts were inserted according to the manufacturer's instructions. A silver amalgam core was placed, and extracted human teeth were prepared to a standard size with a 1 mm gingival chamfer finished on sound dentino A cast was fabricated and cemented, and the specimens were thermocycled. The test samples were secured to an Instron testing machine and loaded until failure. Fracture patterns were recorded, fractured surface areas were measured, and compressive stresses were calculated. However, there were no statistically significant differences among threaded posts in each test group.

A comparison of the apical seals achieved using retrograde amalgam fillings and the Nd:YAG laser

The purpose of this in vitro study was to compare the apical seals achieved using retrograde amalgam fillings or the Nd:YAG laser. Freshly extracted teeth were randomly separated into groups that would have their apices treated either with a Nd:YAG laser or retrograde amalgam. After instrumentation and obturation, bacterial reservoirs were prepared in the coronal portion of canals. Teeth to receive retrofillings had their apices prepared and amalgams placed. Teeth to be lasered had no apical preparations. Teeth and culture media were then sterilized by irradiation. Streptococcus salivarius was deposited in the opened bacterial reservoirs. At intervals, culture media with an indicator in culture chambers was observed for color change. Specimens that demonstrated color change were cultured for S. salivarius. Under the conditions of this in vitro study, no statistically significant difference was found in bacterial leakage between the laser-treated group and the retrograde amalgam group.

Regional changes in amino acid levels of the neonate rat brain during anoxia and recovery

The aim of this study was to compare the changes in amino acids (alanine, aspartate, GABA, glutamate, glutamine, glycine, serine taurine) that are produced in different regions of the neonate brain (telencephalon, diencephalon cerebellum, brain stem) following a survivable period of anoxia and after the re-establishment of air respiration. Anoxia provoked different responses in the different regions. The changes during the anoxic period were as follows. In the brain stem there was a decrease in aspartate, in the telencephalon there was a significant increase in GABA and alanine and a decrease in aspartate, in the diencephalon, glutamate and GABA increased, and in the cerebellum, glycine and alanine levels were enhanced. The changes during recovery were even more dissimilar. Here the greatest shifts were seen in the brain stem with increases in glutamine, GABA, aspartate, glycine, serine, alanine, and taurine. In the telemcephalon glutamate fell and alanine increased, in the diencephalon GABA increased, and in the cerebellum, glutamate fell while glycine and alanine increased. In none of the major brain regions did the pattern of changes in neurotransmitters correspond to that seen in anoxic tolerant species.

Unchanged [3H]MK-801 binding and increased [3H]flunitrazepam binding in turtle forebrain during anoxia

In order to determine if functional changes in N-methyl-D-aspartate receptors and GABAA receptors play a role in the remarkable anoxia tolerance of freshwater turtle brain, we used autoradiographic techniques to assay [3H]MK-801 and [3H]flunitrazepam binding in turtle forebrain after turtles had been subjected to anoxia for 2 or 6 h. The effects of glutamate, glycine, competitive N-methyl-D-aspartate antagonists, glycine antagonists, polyamines, magnesium, and zinc on [3H]MK-801 binding were the same in anoxic and control turtle forebrains. These results indicate that NMDA receptor regulation plays no role in the adaptive responses to anoxia in turtle brain. In contrast, [3H]flunitrazepam binding was significantly increased in the anoxic dorsal cortex and striatum. The most parsimonious explanation for elevated benzodiazepine receptor binding is that the rise in extracellular GABA levels known to accompany anoxia enhances benzodiazepine receptor affinity. It is possible, however, that GABAA receptor upregulation during anoxia increases the effectiveness of the inhibitory action of released GABA and contributes to the anoxia tolerance of turtles.

Intrahepatic biliary stones: imaging features and a possible relationship with ascaris lumbricoides

Intrahepatic (IH) biliary stones are common in East Asia as part of a disease known as Oriental cholangiohepatitis (OCH). At a hospital serving non-Oriental communities, 40 patients were diagnosed on ultrasound (US) during an 8-year period as having IH stones. Follow-up showed that the diagnosis was false in three cases. In the 37 patients with IH stones, 33 conventional retrograde cholangiograms were done; 26 underestimated the IH abnormalities or missed them entirely. Computed tomography (CT) was done in 15 of these 37 patients; the attenuation of the stones was found to be only slightly above that of liver. The evidence that Ascaris lumbricoides was the cause of IH stones in our patients was that: they came mainly from communities in which A. lumbricoides infestation is virtually universal at some stage of childhood, and none from communities in which it is infrequent; their average age was younger than that of patients with conventional gall-stones, fitting with the fact that infestation is predominantly in childhood; A. lumbricoides is the only parasite in our region that invades the biliary system; the histories of the first 12 of the 37 patients had been investigated for intestinal infestation, and were all positive; and 12 of the 37 showed evidence at some time of roundworms or remnants in the biliary system, either within the US appearance of the stones ('bundles' and 'pipes') or separately on US, surgery or duodenoscopy. Biliary strictures, which occur in OCH, were not seen in our patients.

Addition of fresh amalgam to existing amalgam: microleakage study

The purpose of this in vitro study was to determine whether adhesive lining materials reduce microleakage in amalgam restorations, and to observe the degree of microleakage at the interface between freshly placed (new) and existing (old) amalgam. Forty-eight specimens were used in the experimental groups. The materials used to study microleakage in this investigation were: copal varnish, a dentin bonding agent (Clearfil New Bond), and a 4-META adhesive (Amalgambond). No significant difference in microleakage was found at the interfaces between freshly placed and existing amalgam. Significantly less microleakage was noted in specimens using the 4-META adhesive and the dentin bonding agent as compared to specimens in which no lining material was placed. Significantly less microleakage was noted in specimens using the 4-META adhesive compared to specimens using cavity varnish.