Single fetal demise in monochorionic pregnancies: incidence and patterns of cerebral injury.

OBJECTIVE: To evaluate the incidence, type and severity of cerebral injury in the surviving monochorionic (MC) cotwin after single fetal demise in twin pregnancies. METHODS: All MC pregnancies with single fetal demise that were evaluated at the Leiden University Medical Center between 2002 and 2013 were included. Perinatal characteristics, neonatal outcome and the presence of cerebral injury, observed on neuroimaging, were recorded for all cotwin survivors. RESULTS: A total of 49 MC pregnancies with single fetal demise, including one MC triplet, were included in the study (n = 50 cotwins). Median gestational age at occurrence of single fetal demise was 25 weeks and median interval between single fetal demise and live birth was 61 days, with a median gestational age at birth of 36 weeks. Severe cerebral injury was diagnosed in 13 (26%) of the 50 cotwins and was detected antenatally in 4/50 (8%) and postnatally in 9/50 (18%) cases. Cerebral injury was mostly due to hypoxic-ischemic injury resulting in cystic periventricular leukomalacia, middle cerebral artery infarction or injury to basal ganglia, thalamus and/or cortex. Risk factors associated with severe cerebral injury were advanced gestational age at the occurrence of single fetal demise (odds ratio (OR), 1.14 (95% CI, 1.01-1.29) for each week of gestation; P = 0.03), twin-twin transfusion syndrome developing prior to single fetal demise (OR, 5.0 (95% CI, 1.30-19.13); P = 0.02) and a lower gestational age at birth (OR, 0.83 (95% CI, 0.69-0.99) for each week of gestation; P = 0.04). CONCLUSIONS: Single fetal demise in MC pregnancies is associated with severe cerebral injury occurring in 1 in 4 surviving cotwins. Routine antenatal and postnatal neuroimaging, followed by standardized long-term follow-up, is mandatory.

Renal failure after single fetal demise in monochorionic twins: incidence and description of a case.

Single intrauterine fetal demise in monochorionic (MC) twins may result in acute exsanguination from the surviving twin into the low-pressure circulation of the demised co-twin through the vascular anastomoses. This may lead to severe hypoxic-ischemic injury in the surviving twin due to hypovolemia, hypotension and anemia, resulting in multiorgan damage. Most studies in single fetal demise in MC twin pregnancies have reported on the risk of cerebral injury. The aim of our study was to explore the incidence and severity of renal damage in surviving MC twins after intrauterine co-twin death. We reviewed all cases of MC twins with single fetal demise presented over a 10-year period at our center. One of the 44 (2.3%) surviving co-twins was diagnosed with severe renal damage. We describe this case in detail, as it provides valuable insights into the pathogenesis of renal and other organ failure after MC co-twin death.

Management of twin anemia-polycythemia sequence using intrauterine blood transfusion for the donor and partial exchange transfusion for the recipient.

Twin anemia-polycythemia sequence (TAPS) is a rare condition which may occur either spontaneously in uncomplicated monochorionic twin pregnancies or may develop after laser treatment in twin-twin transfusion syndrome. TAPS is characterized by a large intertwin discordance in hemoglobin levels without discordance in amniotic fluid levels, and may lead to severe complications including fetal hydrops, hematological morbidity and perinatal mortality. Several treatments have been proposed including intrauterine transfusion, laser surgery, elective delivery and expectant management. The optimal treatment remains unclear. In this case series we report 3 TAPS cases managed recently at our center with a combination of intrauterine blood transfusion for the anemic twin and intrauterine partial exchange transfusion for the polycythemic twin. In 1 case, the donor was found to have severe cerebral injury on neuroimaging examination. We propose etiologic mechanisms for cerebral injury in TAPS, discuss the rationale behind this treatment alternative, and evaluate the pros and cons of the various management options.

Nanoscale physico-mechanical properties of an aging resistant ZTA composite.

OBJECTIVE: To characterize the effects of aging on the nanomechanical properties and 3D surface topographical parameters of an experimental Zirconia Toughened Alumina (ZTA) composite compared to its respective individual counterpart materials. METHODS: Disk-shaped specimens comprised of three material groups were processed: 1) ZTA 70/30 (70% alumina reinforced with 30% second-generation 3Y-TZP); 2) Zpex (Second-generation 3Y-TZP), and; 3) Al2O3 (High purity Alumina) (n = 10/material, 12 × 1 mm). After synthesis, ceramic powders were pressed, the green-body samples were sintered and polished. Nanoindentation testing was performed to record elastic modulus (E) and hardness (H). Interferometry was utilized to assess 3D surface roughness parameters (Sa, Sq), while X-ray diffraction (XRD) and scanning electron microscope (SEM) assessed the crystalline content and microstructure. All tests were performed before and after simulated aging (134°C, 2.2 bar, 20 h). Statistical analyses were performed using linear mixed-model and least square difference pos-hoc tests (α = 5%). RESULTS: XRD spectra indicated increase of monoclinic peaks for Zpex (~18%) relative to ZTA 70/30 (~2.5%) after aging. Additionally, aging did not affect the surface roughness parameters of ZTA 70/30 and Al2O3, although a significant increase in Sa was recorded for Zpex following aging (~90 nm) (p < 0.001). Al2O3 yielded the highest H and E values (H:21 GPa, E: 254 GPa), followed by ZTA 70/30 (H: 13 GPa, E: 214 GPa) and Zpex (H:11 GPa, E: 167 GPa), all significantly different (p < 0.03). CONCLUSION: ZTA 70/30 and Al2O3 presented high hydrothermal stability with respect to all evaluated variables, where artificial aging significantly increased the monoclinic content and surface roughness of Zpex.

Aging resistance of an experimental zirconia-toughened alumina composite for large span dental prostheses: Optical and mechanical characterization.

PURPOSE: To synthesize a zirconia-toughened alumina (ZTA) composite with 85% alumina matrix reinforced by 15% zirconia and to characterize its optical and mechanical properties before and after artificial aging, to be compared with a conventional dental zirconia (3Y-TZP). MATERIAL AND METHODS: After syntheses, ZTA and 3Y-TZP powders were uniaxially and isostatically pressed. Green-body samples were sintered and polished to obtain 80 disc-shaped specimens per group (12 × 1 mm, ISO 6872:2015). The crystalline content and microstructure were characterized by X-ray diffraction (XRD) and scanning electron microscope (SEM). Optical properties were determined by the calculation of contrast ratio (CR) and translucency parameter (TP) using reflectance data. Mechanical properties were assessed by Vickers hardness, fracture toughness and biaxial flexural strength test (BFS). All analyses were conducted before and after artificial aging (20h, 134 °C, 0.22 MPa). Optical parameters and microhardness differences were evaluated through repeated-measures analysis of variance (p < 0.05). BFS data were analyzed using Weibull statistics (95% CI). RESULTS: The synthesis of the experimental ZTA composite was successful, with 98% of theoretical density, as shown in the SEM images. XRD patterns revealed typical zirconia and alumina crystalline phases. ZTA optical properties parameters showed no effect of aging, with a high CR and low TP values denoting a high masking-ability. 3Y-TZP presented lower masking-ability and aging significantly affected its optical properties. ZTA Vickers hardness, fracture toughness and Weibull parameters, including characteristic stress and Weibull modulus were not influenced by aging, while 3Y-TZP presented a significant decrease in characteristic stress and increase in fracture toughness after aging. The ZTA probability of survival for missions of 300 and 500 MPa was estimated at ~99% validating its use for 3-unit posterior fixed dental prostheses (FDP), and no different from conventional 3Y-TZP. At high-stress mission (800 MPa) a significant decrease in probability of survival was observed for aged 3Y-TZP (84%) and for immediate and aged ZTA (73 and 82% respectively). CONCLUSION: The ZTA composite presented a dense microstructure, with preservation of the crystalline content, optical and mechanical properties after artificial aging, which encourages future research to validate its potential use for large span FDP.

Microstructural, mechanical, and optical characterization of an experimental aging-resistant zirconia-toughened alumina (ZTA) composite.

OBJECTIVE: To evaluate the effect of aging on the microstructural, mechanical, and optical properties of an experimental zirconia-toughened alumina composite with 80%Al2O3 and 20%ZrO2 (ZTA Zpex) compared to a translucent zirconia (Zpex) and Alumina. METHODS: Disc-shaped specimens were obtained by uniaxial and isostatic pressing the synthesized powders (n = 70/material). After sintering and polishing, half of the specimens underwent aging (20 h, 134 °C, 2.2 bar). Crystalline content and microstructure were evaluated using X-ray diffraction and scanning electron microscopy, respectively. Specimens underwent biaxial flexural strength testing to determine the characteristic stress, Weibull modulus, and reliability. Translucency parameter (TP) and Contrast ratio (CR) were calculated to characterize optical properties. RESULTS: ZTA Zpex demonstrated a compact surface with a uniform dispersion of zirconia particles within the alumina matrix, and typical alumina and zirconia crystalline content. ZTA Zpex and alumina exhibited higher CR and lower TP than Zpex. ZTA Zpex and Zpex showed significantly higher characteristic stress relative to alumina. While aging did not affect optical and mechanical properties of ZTA Zpex and alumina, Zpex demonstrated a significant increase in translucency, as well as a in characteristic stress. Alumina reliability was significantly lower than others at 300 MPa, ZTA Zpex and Zpex reliability decreased at 800 MPa, except for aged Zpex. SIGNIFICANCE: While aging did not affect the mechanical nor the optical properties of ZTA Zpex and alumina, it did alter both properties of Zpex. The results encourage further investigations to engineer ZTA as a framework material for long span fixed dental prostheses specially where darkened substrates, such as titanium implant abutments or endodontically treated teeth, demand masking.

Substance P phenotype defines specificity of c-fos induction by cocaine in developing rat striatum.

Activation of c-fos, a member of the class of immediate early genes that act as transcription factors, may be one of the initial molecular mechanisms underlying plastic changes in gene expression in response to drugs of abuse. By combining c-fos (radioactive) in situ hybridization histochemistry with nonradioactive in situ hybridization histochemistry for mRNAs encoding other striatal markers [preprotachykinin (substance P), proenkephalin, and D1 and D2 receptors], we have identified the cellular phenotype of striatal neurons activated by acute administration of cocaine to P8, P15, P28, and adult rats. At each age examined, substance P+, enkephalin- striatal neurons were the predominant class of cells in which cocaine induced c-fos gene expression. In addition, the topography of cellular activation at each age examined was distinct and reflected the topography of distribution of cells expressing high levels of substance P mRNA. We conclude that there is a marked specificity of cellular activation in striatum following acute cocaine administration restricted predominantly to subsets of substance P-expressing cells, with age-specific patterns in their topographic distribution.

Postnatal age defines specificity of immediate early gene induction by cocaine in developing rat brain.

Clinical and animal data suggest that exposure of developing brain to cocaine has adverse consequences. One candidate mechanism for such effects is drug regulation of gene expression. In adult rats, cocaine induces expression of nuclear immediate early genes with specific spatial and temporal patterns. The products of such genes (e.g., c-Fos, c-Jun, and Zif/268) subserve the coupling of cell surface receptor stimulation to transcriptional regulation. Thus, activation of immediate early gene expression in developing brain by cocaine could alter programs of neural gene expression and, thereby, neuronal phenotype and function. We report that, during rat brain development, cocaine produced brain region-specific and developmental age-specific induction of c-fos, c-jun, and zif/268 mRNAs. At each age studied (P8, P15, P28, and adults), we found that acute cocaine administration resulted in a unique cell-specific pattern of c-fos mRNA induction and c-Fos protein expression in striatum. We also observed cocaine-induced activation of AP-1 DNA binding activity in striatal extracts prepared at these different ages, suggesting that the observed induction of c-fos and c-jun may have biological consequences for the developing brain. These findings suggest a mechanism by which cocaine could alter patterns of gene expression during critical developmental periods with differential regional, temporal, and cellular vulnerabilities and, therefore, consequences for developing brain.

Transplacental cocaine exposure. 1: A rodent model.

To characterize the transplacental effects of cocaine on the developing brain, we have developed a mouse model of gestational cocaine exposure. Pharmacokinetic analysis revealed that cocaine and its metabolites (BE, BNE, and NC) were found in fetal brain and plasma at 30 and 120 min following SC administration to embryonic day (E) 17 pregnant Swiss Webster mice. Pregnant dams injected twice daily with cocaine HCl at 20 mg/kg SC from gestational day E8 to E17 (COC) demonstrated less food intake and lower percentage weight gain than vehicle-injected dams allowed access to food ad lib (SAL). A nutritionally paired control group of dams injected with saline vehicle and pair-fed with the COC dams (SPF) demonstrated the lowest percentage weight gain of all three groups. The surrogate fostered offspring of COC and SPF dams demonstrated persistent growth retardation [on postnatal days (P) 1, P9, and P50] and transient brain growth retardation (on P1 and P9) when compared to pups born to SAL dams. We conducted behavioral tests that allowed us to dissociate the indirect effect of cocaine-induced malnutrition from a direct effect of prenatal cocaine administration in altering postnatal behavior. Pups from all three groups were tested for first-order Pavlovian conditioning on P9 or P12, or for the ability to ignore redundant information in a blocking paradigm on P50 or P100. Unlike the SPF and SAL controls, COC mice (i.e., mice born to COC dams) were unable to acquire an aversion to an odor previously paired with shock on P9. This learning deficit was transient because on P12, COC mice trained on the same conditioning task displayed an aversion to the odor that was indistinguishable from the SPF and SAL controls. P50 and P100 COC mice (and to a lesser extent, SPF mice) demonstrated a persistent behavioral deficit in the blocking paradigm, which may reflect alterations in selective attention. We discuss how these findings in our rodent model have developmental implications for human infants exposed to cocaine in utero.

The interaction of blood proteins with alpha-alumina.

The use of alumina (alpha-Al2O3) as a material for cardiovascular applications was investigated on the basis of protein adsorption and thrombus formation on the material. The adsorption of 125I-labelled albumin and fibrinogen from phosphate buffered saline (pH 7.35, 0.100 M NaCl, 8.66 mM KH2PO4 and 41 mM Na2HPO4) solution on ceramic discs of alumina was studied. Both albumin and fibrinogen presented affinity for ceramic surfaces, with adsorptions of 1.47 +/- 0.06 ng/cm2 and 0.198 +/- 0.01 ng/cm2, respectively. Scanning electron micrographs of the alpha-Al2O3 surfaces after contact of the discs with whole human blood showed a thrombogenic behavior of alumina alpha. These results indicate a hemoincompatible property. Although critical surface tension (gamma C: 21.8 dynes/cm) of the disc surfaces determined by contact angle technique of sessile drops indicates that alumina alpha is a biocompatible material, by this criterion, the data reported here indicate that alpha-Al2O3 cannot be used for cardiovascular applications.

A novel Cu,Zn superoxide dismutase from the fungal strain Humicola lutea 110: isolation and physico-chemical characterization.

The fungal strain Humicola lutea 110 produces a mangan- and a copper zinc-containing superoxide dismutases (SOD). In this study, the purification, N-terminal sequence and spectroscopic properties of the new Cu,Zn SOD are described. The preparation of the pure metalloenzyme was achieved via treatment of the strain with acetone followed by gel and ion exchange chromatography. The protein consists of 302 amino acid residues and has a molecular mass of approximately 32 kDa, as determined by PAG electrophoresis and 3100 U mg-1 protein-specific activity. It is a dimeric enzyme with two identical subunits of 15,950 Da, as indicated by SDS-PAGE, mass spectroscopic and amino acid analysis. The N-terminal sequence analysis of the Cu,Zn SOD from the fungal strain revealed a high degree of structural homology with enzymes from other eukaryotic sources. Conformational stability and reversibility of unfolding of the dimeric enzyme were determined by fluorescence and circular dichroism (CD) spectroscopy. The critical temperature of deviation from linearity (Tc) of the Arrhenius plot ln (Q-1(-1)) vs. 1/T was calculated to be 68 degrees C and the respective activation energy for the thermal deactivation of the excited indole chromophores is 42 kcal mol-1. The melting temperatures (Tm) were determined by CD measurements to be 69 degrees C for the holo- and 61 degrees C for the apo-enzyme. The fluorescence emission of the Cu,Zn SOD is dominated by 'buried' tryptophyl chromophores. Removal of the copper-dioxygen system from the active site caused a 4-fold increase of the fluorescence quantum yield and a 10 nm shift of the emission maximum position towards higher wavelength.

5-HT3 receptor activation is required for induction of striatal c-Fos and phosphorylation of ATF-1 by amphetamine.

Dopamine (DA) has been shown to be required for the induction of striatal gene expression by psychostimulants. However, direct DA agonists or selective inhibitors of DA reuptake are relatively weak inducers of striatal gene expression compared with cocaine or amphetamine. So although necessary, DA alone is not sufficient to mediate the full gene induction response to psychostimulants. In addition to its actions on the DA transporter, amphetamine also enhances serotonin (5-HT) release in the striatum. In this study, we investigated the mechanism by which 5-HT contributes to the regulation of striatal gene expression by amphetamine. We found that selective lesions of serotonergic terminals in the rat forebrain using 5,7-dihydroxytryptamine prevented the full induction of striatal c-Fos by 4 mg/kg amphetamine. Furthermore, amphetamine-induced striatal c-Fos was completely inhibited by administration of the 5-HT3 receptor antagonist, MDL-72222, but not by the 5-HT2A/2C receptor antagonist, ritanserin. Consistent with this finding, the induction of c-Fos by 5-HT in primary cultures of E18 striatal neurons devoid of DA input was blocked by the 5-HT3 receptor antagonists, MDL-72222 and ICS 205-930, but not by 5-HT2A/2C antagonism. Additionally, blockade of 5-HT3 receptors by MDL-72222 inhibited the phosphorylation of activating transcription factor-1 (ATF-1) at Ser63 by amphetamine, but not the phosphorylation of cAMP response element binding protein (CREB) at Ser133. These results suggest that 5-HT3 receptor activation may be required for amphetamine-induced expression of ATF-1-regulated target genes in the striatum, which may include c-Fos.

Effect of glucose on the superoxide dismutase production in fungal strain Humicola lutea.

The effect of glucose on superoxide dismutase (SOD) activity produced in Humicola lutea 110 was determined. The relatively high glucose concentration in the medium did not repress SOD levels in the cells. Glycerol, a nonfermentable carbon source, caused a slight stimulation of SOD synthesis. Furthermore, the specific rates of enzyme production in the medium with different glucose concentration showed an insignificant difference. Cyclic AMP had no effect on SOD levels. The shift in metabolism as glucose was depleted resulted in an increase in the rate of synthesis of both isocitric dehydrogenase and SOD. Pentachlorophenol and paraquat, which cause the production of superoxide radicals, caused an increase in SOD activity. These results led us to conclude that it is superoxide ion rather than glucose that is controlling SOD levels.

Involvement of cAMP-dependent protein kinase in the nucleus accumbens in cocaine self-administration and relapse of cocaine-seeking behavior.

cAMP-dependent protein kinase (PKA) in the nucleus accumbens (NAc) has been implicated in cocaine addiction because (1) cocaine reinforcement is mediated by dopamine receptors that modulate cAMP formation, and (2) repeated exposure to cocaine upregulates the cAMP system in NAc neurons. This study tested PKA involvement in cocaine self-administration and relapse of cocaine-seeking behavior by infusing cAMP analogs that activate or inhibit PKA into the NAc of rats. Bilateral intra-NAc infusions of the PKA inhibitor Rp-cAMPS reduced baseline cocaine self-administration, shifted the dose-response curve for cocaine self-administration to the left, and induced relapse of cocaine-seeking behavior after extinction from cocaine self-administration, consistent with an enhancement of cocaine effects in each paradigm. In contrast, pretreatment with intra-NAc infusions of a PKA activator, Sp-cAMPS or dibutyryl cAMP, increased baseline cocaine self-administration during the second hour of testing and shifted the dose-response curve to the right, consistent with an antagonist-like action. After extinction from cocaine self-administration, similar infusions of Sp-cAMPS induced generalized responding at both drug-paired and inactive levers. As an index of PKA activity in vivo, NAc infusions of Rp-cAMPS reduced basal levels of dopamine-regulated phosphoprotein-32 phosphorylation and blocked amphetamine-induced increases in cAMP response element-binding protein (CREB) phosphorylation. Conversely, NAc infusions of Sp-cAMPS increased phosphorylation of CREB. Together, these results suggest that sustained upregulation of the cAMP system in the NAc after repeated cocaine exposure could underlie tolerance to cocaine reinforcement, whereas acute inhibition of this system may contribute to drug craving and relapse in addicted subjects.

Isolation and characterization of a novel superoxide dismutase from fungal strain Humicola lutea 110.

A novel thermostable MnSOD was purified to electrophoretic homogeneity from the fungal strain Humicola lutea 110. The preparation of the pure metalloenzyme was performed using treatment with acetone followed by ion exchange and gel permeation chromatography. We found that the activity of this enzyme comprises about 80% of the total superoxide dismutase activity in the crude extract, containing two proteins: MnSOD and Cu/ZnSOD. The MnSOD has a molecular mass of approximately 76 kDa and 7200 U/mg protein specific activity. It is a tetrameric enzyme with four identical subunits of 18 860 Da each as indicated by SDS-PAGE, amino acid analysis and mass spectrometry. N-terminal sequence analysis of MnSOD from the fungal strain revealed a high degree of structural homology with enzymes from other eukaryotic sources. Physicochemical properties were determined by absorption spectroscopy and circular dichroism measurements. The UV absorption spectrum was typical for an MnSOD enzyme, but displayed an increased absorption in the 280 nm region (epsilon280 = 10.4 mM(-1). cm(-1)), attributed to aromatic amino acid residues. The CD data show that MnSOD has two negative Cotton effects at 208 and 222 nm allowing the calculation of its helical content. The ellipticity at 222 nm is 6800 deg. x m(2) x dmol(-1) and thus similar to the values reported for other MnSODs. The MnSOD from H. lutea 110 is stable over a wide range of pH (4.5-8), even in the presence of EDTA. The enzyme is thermostable at 70-75 degrees C, and more stable than MnSODs from other sources.

The interation of blood proteins with alpha-alumina

The use of alumina (Ó-Al2O3) as a material for cardiovascular applications was investigated on the basis of protein adsorption and thrombus formation on the material. The adsorption of 125I-labelled albumin and fibrinogen from phosphate buffered saline (pH 7.35, 0.100 M NaCl, 8.66 mM KH2PO4 and 41 mM Na2HPO4) solution on ceramic discs of alumina was studied. Both albumin and fibrinogen presented affinity for ceramic surfaces, with adsorptions of 1.47 + or - 0.6 ng/cm2 and 0.198 + or - 0.01 ng/cm2, respectively. Scanning electron micrographs of the Ó-Al2O3 surfaces after contact of the discs with whole human blood showed a thrombogenic behavior of alumina alpha. These results indicate a hemoincompatible property. Although critical surface tension (YC: 21.8 dynes/cm) of the disc surfaces determined by contact angle technique of sessile drops indicates that alumina alpha is a biocompatible material, by this criterion, the data reported here indicate that Ó-Al2O3 cannot be used for cardiovascular applications