Comparison of lumbar and shunt cerebrospinal fluid specimens for cytologic detection of leptomeningeal disease in pediatric patients with brain tumors

PURPOSE

Leptomeningeal disease (LMD) significantly affects the prognosis and treatment of pediatric patients with primary CNS tumors. Cytologic examination of lumbar CSF is routinely used to detect LMD. To determine whether examination of CSF obtained from ventricular shunt taps is a more sensitive method of detecting LMD in these patients, we designed a prospective study to compare the findings of cytologic examinations of CSF obtained from concurrent lumbar and ventriculoperitoneal (VP) shunt taps.

PATIENTS AND METHODS

As a part of diagnostic staging, follow-up testing, or both, 52 consecutive patients underwent concurrent lumbar and shunt taps on 90 separate occasions, ranging from the time of diagnosis to treatment follow-up. CSF from both sites was examined cytologically for malignant cells.

RESULTS

The median age of the 28 males and 24 females was 7.5 years (range, 0.6 to 21.4 years). The primary CNS tumors included medulloblastoma (n = 29), astrocytoma (n = 10), ependymoma (n = 5), germinoma (n = 3), atypical teratoid rhabdoid tumor (n = 2), choroid plexus carcinoma (n = 2), and pineoblastoma (n = 1). Each site yielded a median CSF volume of 1.0 mL. Fourteen of 90 paired CSF test results were discordant: in 12, the cytologic findings from shunt CSF were negative for malignant cells, but those from lumbar CSF were positive; in two, the reverse was true. Malignant cells were detected at a higher rate in lumbar CSF than in shunt CSF (P =.0018). When repeat analyses were excluded, examination of lumbar CSF remained significantly more sensitive in detecting malignant cells (P =.011). Analysis of the subset of patients with embryonal tumors showed similar results (P =.0008).

CONCLUSION

Cytologic examination of lumbar CSF is clearly superior to cytologic examination of VP shunt CSF for detecting leptomeningeal metastases in pediatric patients with primary CNS tumors.

The association of opportunistic infections with the occurrence of trimethoprim/sulfamethoxazole hypersensitivity in patients infected with human immunodeficiency virus

Hypersensitivity from trimethoprim/sulfamethoxazole (TMP/SMX) has been linked to a reactive nitroso intermediate from sulfamethoxazole metabolism, which may be altered in patients with human immunodeficiency virus (HIV) infection. The authors determined the clinical factors that are associated with TMP/SMX hypersensitivity in patients with HIV. In a case control study, 54 controls currently tolerating TMP/SMX prophylaxis were randomly matched by date of hypersensitivity reaction in case patients to 28 patients with a history of a rash consistent with erythema multiforme from TMP/SMX. Demographic data, coadministered medications, laboratory data, and histories of opportunistic infections were extracted on all patients. A highly significant association was observed between the number of opportunistic infections and the occurrence of TMP/SMX hypersensitivity (p < 0.001), despite comparability of CD4 counts between case patients and controls (p > 0.1). A tendency for protection from TMP/SMX hypersensitivity in blacks was also observed (p = 0.066). These observations suggest that the mechanisms by which HIV produces cellular immune dysfunction and alters drug detoxification may be linked.

Intrapatient consistency of imaging biodistributions and their application to predicting therapeutic doses in a phase I clinical study of 90Y-based radioimmunotherapy

Intrapatient variation in the biodistribution of the chimeric monoclonal antibody cT84.66 was assessed in 19 patients having a variety of carcinoembryonic antigen (CEA) positive tumors. The two studies, including whole-body imaging and blood and urine specimen collections, were conducted within 14 days of each other using (111)In-cT84.66 at a fixed total protein dose of 5 mg per patient per study. An initial pretherapy infusion of (111)In-cT84.66 was administered followed by a therapy coinfusion of (111)In-ct84.66 and 90Y-cT84.66 A closed five-compartment model was used to integrate source organ activity curves as residence time inputs into the MIRDOSE3 program. Normal organ absorbed doses were estimated for 90Y-cT84.66, the corresponding radiotherapeutic agent. For the two (111)In-cT84.66 biodistributions, all data were modeled with a R2 value of between 0.72 and 1.00 with the exception of the urine data taken during therapy. This was due to the need of diethylenetriaminepentaacetic acid during the therapy phase because of the possibility that yttrium might escape from the chelator attached to the antibody. With the assurance that the biodistributions were reproducible, we were able to estimate the 90Y-cT84.66 absorbed doses on a per-patient basis. Concordance coefficients showing the agreement between the imaging and therapy phase dose estimates were between the 0.60 and 0.99 levels for liver, spleen, red marrow, total body, and other organ systems. Median results were: 27, 17, and 2.7 rad/mCi of 90Y-cT84.66 for liver, spleen, and red marrow, respectively. Because of decreases in platelets and white cells as the amount of 90Y was increased, dose-limiting toxicity was found at 22 mCi/m2. We conclude that patient biodistributions were consistent over time to 14 days so as to allow absorbed dose estimation in a radioimmunotherapy trial involving the cT84.66 anti-CEA antibody.

[The role of activation of p38 MAPK induced by LPS in TNF-alpha gene expression]

OBJECTIVE

To study the molecular mechanisms of TNF-alpha expression induced by LPS for the exploring of novel methods to prevent and treat clinical patients of endotoxic shock.

METHODS

Protein kinase assay was used to detect the kinase activity stimulated by LPS; Confocal laser scan technique was used to show the translocation of p38 on the activation; RT-PCR and reporter gene system were used to study the molecular mechanism of TNF-alpha gene transcription.

RESULTS

In RAW cells, p38 was activated on the stimulation of LPS, and activated p38 moved into nucleus from cytosol. TNF-alpha mRNA increased on the stimulation of LPS and the increased promoter transactivity induced by LPS could be inhibited significantly by specific inhibitor for p38.

CONCLUSION

p38 MAPK was activated on the stimulation of LPS, which brought about its translocation to the nucleus to act on transcription factors to regulate cellular processes. p38 MAPK is an important regulator of TNF-alpha gene expression induced by LPS.

[Differential diagnosis and operative timing of intramedullary spinal cord tumors]

OBJECTIVE

To discuss the differential diagnosis of various kinds of intramedullary spinal cord tumors, and choose the right operative timing.

METHODS

On grading the dysfunction of the movement, an analysis has been made statistically for 147 cases with 160 tumors resected by microneurosurgery and confirmed pathologically. Their neuroimage have been also compared.

RESULTS

The clinical manifestations of main kinds of intramedullary spinal cord tumors are not significantly different, but there are certain characteristic features in their neuroimage. The tumors of grade 0 group (normal movement) are obviously smaller than those of other grades groups. The pre- and post-operative grades of motor disturbance show a better, positive linear correlation.

CONCLUSIONS

MRI, particularly its enhancement, can differentiate an ependymoma from astrocytoma and hemangioblastoma in most cases. A satisfactory result can be achieved to resect the tumor immediately by using the minimally invasive, microsurgical techniques.

[Clinical evaluation on parenteral nutrition in neonatal disease]

Thirty cases of neonatal disease were treated with parenteral nutrition (PN) as an adjuvant treatment and compared with the control group (n = 30). The body weight and plasma albumin increased remarkably in the PN group (P < 0.01, P < 0.05). No significant metabolic complication was occurred (P > 0.05). PN proved to be a safe and effective approach for neonatal patients, in which nutritional admixture components were adjusted day by day according to gestational age, body weight, disease course and monitor indexes to match the actual gastric intestinal tract function.

Tetrodotoxin suppresses morphological enhancement of the metastatic MAT-LyLu rat prostate cancer cell line

Voltage-gated Na+ channels are expressed by highly metastatic MAT-LyLu cells, but not by poorly metastatic AT-2 cells, derived from the rodent Dunning model of prostatic cancer. We have investigated the possible involvement of these channels in the morphological development of the cells. Incubation of both the MAT-LyLu and the AT-2 cell line for 24 h with the Na+ channel blocker tetrodotoxin (TTX) at 6 microM altered the morphology only of the MAT-LyLu cell line. TTX produced significant decreases in: (a) cell process length and (b) field diameter, and increases in (c) cell body diameter and (d) process thickness. Importantly, 6 microM TTX had no significant effects on proliferation rates or cellular toxicity. The results suggest that Na+ channel activity plays a significant role in determining the morphological development of MAT-LyLu cells in such a way as to enhance their metastatic potential.

Y-chromosome specific YCAII, DYS19 and YAP polymorphisms in human populations: a comparative study

Two hypervariable Y-specific markers, the YCAII and DYS19 STRs, and the more stable Y Alu Polymorphism (YAP) have been analysed in about 1400 individuals of 21 different populations, mainly from Europe but also from the Middle East, Africa and Asia. On the basis of the frequency distributions of these three Y-markers we compare, using different statistical analyses, their power in detecting population genetic structure and in distinguishing closely related groups. The pattern of populations' genetic affinities inferred from the three markers considered altogether suggests a strong genetic structure that, with a few exceptions, broadly corresponds to the linguistic relatedness and/or geographic location of the sampled populations.

A comparison of the preventive effects of lanthanides and fluoride on human experimental root surface carious-like lesions

OBJECTIVE

To investigate the mechanisms of lanthanides prevention of human root surface carious-like lesions and to compare the effectiveness of lanthanum (La) with that of cerium (Ce) and fluoride (F). Various treatment procedures were also compared.

MATERIALS AND METHODS

Acetic buffers containing lanthanum, cerium, and fluoride (500 ppm) were used individually or in combination to treat 48 cementum-dentin samples. The acid-resistant capacity of various treatment procedures was evaluated by means of scanning electron microscope, electron microprobe, and polarizing light microscope analyses.

RESULTS

The acid-resistant effects of lanthanide element were comparable to those of fluoride, and their acid-resistant effects were even stronger when combined with fluoride and cerium. These effects are likely due to the formation of La(Ce)HAP, FLa(Ce)HAP, and lanthanum/cerium phosphate compounds.

CONCLUSION

Combined F/La(Ce) was more effective in the prevention of root surface caries than were lanthanides alone.

Relationship between fossa-condylar position, meniscus position, and morphologic change in patients with Class II and III malocclusion

OBJECTIVE

To evaluate fossa-condylar-meniscus morphologic changes in patients with skeletal and dental Class III and Class II division 1 and 2 malocclusion to determine which type is related to internal derangement of the temporomandibular joint (TMJ) and whether the variation of TMJ structure is related to a particular type of malocclusion.

MATERIALS AND METHODS

Seventy-two pretreatment orthodontic patients, ranging in age from 10 to 27 years, underwent examination of the right and left TMJs with corrected Schöller's position radiographs. Bilateral TMJ relationships of the fossa-condyle were examined through subjective evaluation and linear and area measurements. In addition, in 20 of the 72 patients, meniscus positions and morphologic changes were imaged with a 0.5 T sagittal magnetic resonance imaging system on the right and left TMJ.

RESULTS

(1) The variation of condyle-fossa positions for identical types of malocclusion was very large. (2) Skeletal and functional Class III malocclusion patients demonstrated significantly more anteriorly positioned condyles. (3) Class II division 1 patients showed concentrically positioned condyles, but with slightly anterior displacement. (4) Class II division 2 patients demonstrated more posteriorly positioned condyles. (5) When condyles were in anterior or concentric positions, meniscus positions and morphology were normal and in concavoconcave shapes. (6) When condyles were in posterior positions, most meniscus positions were in normal or slightly anterior range and their shapes were also concavoconcave. The rest were significantly more anterior and their shapes were abnormal, as evidenced by thickened anterior bands.

CONCLUSION

Class III and Class II division 1 malocclusion demonstrated normal structure and function of the TMJ. Class II division 2 malocclusion was obviously associated with abnormal structure and function of the TMJ.

Generation of bcr-abl specific cytotoxic T-lymphocytes by using dendritic cells pulsed with bcr-abl (b3a2) peptide: its applicability for donor leukocyte transfusions in marrow grafted CML patients

Dendritic cells (DC), the most potent 'professional' antigen-presenting cells, hold promise for improving the immunotherapy of cancer. In this study, we investigated the ability of normal donor DC pulsed ex vivo with 12 mer bcr-abl (b3a2) peptide to generate b3a2-specific autologous or HLA-identical sibling donor's cytotoxic T-lymphocytes (CTL). DC that were grown from normal peripheral blood adherent cells or purified DC precursors in the presence of GM-CSF and IL-4, were pulsed with b3a2-peptide then were induced to become mature and functional cells by the addition of TNF-alpha. These peptide-pulsed mature DC elicited a potent b3a2-specific CTL response in vitro. The b3a2-peptide pulsed DC-primed peripheral blood lymphocytes (PBL) displayed significantly higher cytotoxic activity compared with peptide non-pulsed DC-primed PBL against target cells, which are b3a2 positive marrow cells derived from HLA-identical sibling chronic myelogenous leukemia (CML) patient, or peptide-pulsed autologous macrophages (P < 0.001). In addition, the b3a2 peptide-pulsed DC-primed and non-pulsed DC-primed PBL showed no cytotoxic response against peptide non-pulsed autologous macrophages. These findings revealed that normal donor PBL pre-immunized with b3a2-peptide pulsed autologous DC could increase the graft-versus-leukemia effect without exaggerating graft-versus-host-disease. Both CD8+ and CD4+ T lymphocytes were shown to be involved in the effector cell populations. The b3a2 peptide-pulsed DC-primed T cells were significantly superior in their production of GM-CSF and TNF-alpha compared with peptide non-pulsed DC-primed T cells. These intriguing preclinical results imply the feasibility of developing b3a2 peptide-DC based protocol for in vitro sensitization of normal donor leukocytes before donor leukocyte transfusions for patients with CML, who relapsed after HLA-matched sibling bone marrow transplantation.

Chronic in vitro shear stress stimulates endothelial cell retention on prosthetic vascular grafts and reduces subsequent in vivo neointimal thickness

OBJECTIVE

The absence of endothelial cells at the luminal surface of a prosthetic vascular graft potentiates thrombosis and neointimal hyperplasia, which are common causes of graft failure in humans. This study tested the hypothesis that pretreatment with chronic in vitro shear stress enhances subsequent endothelial cell retention on vascular grafts implanted in vivo.

METHODS

Cultured endothelial cells derived from Fischer 344 rat aorta were seeded onto the luminal surface of 1.5-mm internal diameter polyurethane vascular grafts. The seeded grafts were treated for 3 days with 1 dyne/cm2 shear stress and then for an additional 3 days with 1 or 25 dyne/cm2 shear stress in vitro. The grafts then were implanted as aortic interposition grafts into syngeneic rats in vivo. Grafts that were similarly seeded with endothelial cells but not treated with shear stress and grafts that were not seeded with endothelial cells served as controls. The surgical hemostasis time was monitored. Endothelial cell identity, density, and graft patency rate were evaluated 24 hours after implantation. Endothelial cell identity in vivo was confirmed with cells transduced in vitro with beta-galactosidase complementary DNA in a replication-deficient adenoviral vector. Histologic, scanning electron microscopic, and immunohistochemical analyses were performed 1 week and 3 months after implantation to establish cell identity and to measure neointimal thickness.

RESULTS

The pretreatment with 25 dyne/cm2 but not with 0 or 1 dyne/cm2 shear stress resulted in the retention of fully confluent endothelial cell monolayers on the grafts 24 hours after implantation in vivo. Retention of seeded endothelial cells was confirmed by the observation that beta-galactosidase transduced cells were retained as a monolayer 24 hours after implantation in vivo. In the grafts with adherent endothelial cells that were pretreated with shear stress, immediate graft thrombosis was inhibited and surgical hemostasis time was significantly prolonged. Confluent intimal endothelial cell monolayers also were present 1 week and 3 months after implantation. However, 1 week after implantation, macrophage infiltration was observed beneath the luminal cell monolayer. Three months after the implantation in vivo, subendothelial neointimal cells that contained alpha-smooth muscle actin were present. The thickness of this neointima averaged 41 +/- 12 micrometer and 60 +/- 23 micrometer in endothelial cell-seeded grafts that were pretreated with 25 dyne/cm2 shear stress and 1 dyne/cm2 shear stress, respectively, and 158 +/- 46 micrometer in grafts that were not seeded with endothelial cells.

CONCLUSION

The effect of chronic shear stress on the enhancement of endothelial cell retention in vitro can be exploited to fully endothelialize synthetic vascular grafts, which reduces immediate in vivo graft thrombosis and subsequent neointimal thickness.

Modeling and prediction of human behavior

We propose that many human behaviors can be accurately described as a set of dynamic modes (e.g., Kalman filters) sequenced together by a Markov chain. We then use these dynamic Markov models to recognize human behaviors from sensory data and to predict human behaviors over a few seconds time. To test the power of this modeling approach, we report an experiment in which we were able to achieve 95% accuracy at predicting automobile drivers' subsequent actions from their initial preparatory movements.

Comparative performance of Lupinus albus genotypes in response to soil alkalinity

Narrow-leafed lupin (Lupinus angustifolius L.) grows poorly on alkaline soils, whereas white lupin (Lupinus albus L.) grows relatively well. This study aimed at examining genotypic variations of white lupins grown in limed acid and alkaline soils in the glasshouse and to test whether the glasshouse findings correlated with those observed in the field. Twelve white lupin genotypes were tested for their tolerance of limed and alkaline soils in the glasshouse. In limed soils compared with the control soil, genotypic variation in shoot growth ranged from 58 to 80%, root weight from 49 to 72%, and leaf chlorophyll concentration from 47 to 96%. In the alkaline soil, shoot weight ranged from 75 to 110%, root weight from 39 to 63%, and chlorophyll concentration from 58 to 94% of the control. However, iron chlorosis did not negatively correlate with shoot growth of the genotypes on the limed or alkaline soils. The results suggest that iron chlorosis may not be used as a sole indicator for selecting tolerant albus lupins for alkaline soils. Nineteen lines including those used in the glasshouse were compared in the field for their ability to grow on an alkaline clay. Large genotypic variation in early shoot growth was also found; shoot weight on the alkaline soil relative to an acid soil ranged from 38 to 85%. However, growth performance of the white lupin genotypes in response to the alkaline soil did not correlate with those in the glasshouse, indicating that factors other than soil alkalinity might also be important for the growth of albus lupin. Screening techniques to identify tolerant genotypes for alkaline soils need to be further developed.

[The contents of plasma norepinephrine and epinephrine in patients with five types of Gan syndromes in TCM and its significance for diagnosis]

Plasma norepinephrine (NE) epinephrine (E) concentrations in patients with five types of Gan syndromes and relative syndromes were determined. The healthy individuals served as control. The contents of NE and E in Ganyang Huafeng Zheng (5975.8 +/- 305.6 pmol.L-1, 2227.7 +/- 12.57 pmol.L-1) were significantly increased; Ganxue Xu Zheng (1100.4 +/- 105.5, 451.2 +/- 70.9 pmol.L-1) were decreased, and lower than the normal controls. NE and E contents in both Ganyang Shangkang Zheng (3962.6 +/- 354.4, 1225.6 +/- 163.5 pmol.L-1) and Ganhuo Shangyan Zheng (3398.1 +/- 303.8, 1134.4 +/- 146.9 pmol.L-1) were increased remarkably, but there was no difference between them. Plasma NE, E concentrations can be considered as one of the comprehensive laboratory parameters in diagnosis of the four above mentioned Gan syndromes.

Dose escalation trial of indium-111-labeled anti-carcinoembryonic antigen chimeric monoclonal antibody (chimeric T84.66) in presurgical colorectal cancer patients

Chimeric T84.66 (cT84.66) is a high-affinity (1.16x10(11) M(-1)) IgG1 monoclonal antibody against carcinoembryonic antigen (CEA). The purpose of this pilot trial was to evaluate the tumor-targeting properties, biodistribution, pharmacokinetics and immunogenicity of 111In-labeled cT84.66 as a function of administered antibody protein dose.

METHODS

Patients with CEA-producing colorectal cancers with localized disease or limited metastatic disease who were scheduled to undergo definitive surgical resection were each administered a single intravenous dose of 5 mg of isothiocyanatobenzyl diethylenetriaminepentaacetic acid-cT84.66, labeled with 5 mCi of 111In. Before receiving the radiolabeled antibody, patients received unlabeled diethylenetriaminepentaacetic acid-cT84.66. The amount of unlabeled antibody was 0, 20 or 100 mg, with five patients at each level. Serial blood samples, 24-hr urine collections and nuclear images were collected until 7 days postinfusion. Human antichimeric antibody response was assessed up to 6 mo postinfusion.

RESULTS

Imaging of at least one known tumor site was performed in all 15 patients. Fifty-two lesions were analyzed, with an imaging sensitivity rate of 50.0% and a positive predictive value of 76.9%. The antibody detected tumors that were not detected by conventional means in three patients, resulting in a modification of surgical management. Interpatient variations in serum clearance rates were observed and were secondary to differences in clearance and metabolic rates of antibody and antibody:antigen complexes by the liver. Antibody uptake in primary tumors, metastatic sites and regional metastatic lymph nodes ranged from 0.4% to 134% injected dose/kg, resulting in estimated 90Y-cT84.66 radiation doses ranging from 0.3 to 193 cGy/mCi. Thirteen patients were evaluated 1-6 mo after infusion for human antichimeric antibody, and none developed a response. No major differences in tumor imaging, tumor uptake, pharmacokinetics or organ biodistribution were observed with increasing protein doses, although a trend toward increasing blood uptake and decreasing liver uptake was observed with increasing protein dose.

CONCLUSION

Chimeric T84.66 demonstrated tumor targeting comparable to other radiolabeled intact anti-CEA monoclonal antibodies. Its immunogenicity after single administration was lower than murine monoclonal antibodies. These properties make 111In-cT84.66, or a lower molecular weight derivative, attractive for further evaluation as an imaging agent. Yttrium-90 dosimetry estimates predict potentially cytotoxic radiation doses to select tumor sites, which makes 90Y-cT84.66 also appropriate for further evaluation in Phase I radioimmunotherapy trials. Although clinically important changes in biodistribution, pharmacokinetics and tumor targeting with increasing protein doses of 111In-cT84.66 were not demonstrated, the results do suggest that antibody clearance from the blood is driven by hepatic uptake and metabolism, with more rapid blood clearance seen in patients with liver metastases. These patients with rapid clearance and potentially unfavorable biodistribution for imaging and therapy may, therefore, be a more appropriate subset in which to evaluate the role of administering higher protein doses. This underscores the need to further identify, characterize and understand those factors that influence the biodistribution and clearance of radiolabeled anti-CEA antibodies, to allow for better selection of patients for therapy and rational planning of radioimmunotherapy.

Efficient Operation of an Intracavity-Doubled Nd:YVO(4)/KTP Laser End Pumped by a High-Brightness Laser Diode

Using a 1-W high-brightness laser diode as the pump source, we investigated the output characteristics of an intracavity frequency-doubled Nd:YVO(4)/KTP laser. Highly efficient operation was realized based on an optimized cavity design. The second-harmonic output power at 532 nm was measured to be 286.5 mW at an incident pump power of 881.4 mW, corresponding to an optical-to-optical efficiency of 32.5%.

The tyrosyl free radical of recombinant ribonucleotide reductase from Mycobacterium tuberculosis is located in a rigid hydrophobic pocket

The tyrosyl free radical in protein R2-2 of class Ib ribonucleotide reductase (RNR) fromMycobacterium tuberculosis is essential for the enzymatic activity and has an EPR spectrum remarkably similar to that of the tyrosyl radical YD* in PSII. The EPR relaxation properties of the radical suggest a very weak exchange coupling between the two redox centers, the radical and the diferric cluster. The tyrosyl radical gives almost identical EPR spectra in the temperature interval 10-293 K. We conclude that the tyrosyl radical sits in a rigid pocket. Two ring protons and one beta-methylene proton account for the major anisotropic hyperfine interactions. A high-frequency EPR spectrum of the radical showed a resolved gx = 2. 0092, indicating that a hydrogen bond to the phenolic oxygen of the radical is absent. Theoretical modeling studies based on the structural data known for Salmonella typhimurium class Ib RNR protein R2F revealed a hydrophobic wall aligned with the radical harboring residue Y110. The distance between the phenolic oxygen of the radical and the diferric cluster is longer in the two class Ib nrdF R2 proteins than in other characterized class Ia R2 proteins. The tyrosyl radical in protein R2-2 from M. tuberculosis was accessible to direct reduction by dithionite in the absence of a mediator. The radical could be partly regenerated when the system was exposed to O2 after the completion of anaerobic reduction. This indicates that the Fe3+ ions also had become reduced by dithionite.

Photorefractive materials for nonvolatile volume holographic data storage

Optically gated recording and nonvolatile readout in a digital volume holographic data storage system that uses a pair of mutually incoherent light sources during recording and only one for readout were demonstrated recently. This approach used stoichiometric lithium niobate, which after post-growth processing gave rise to an at least two orders of magnitude improvement in sensitivity over the best materials reported previously. It is also shown that by adding certain dopants (iron and manganese) to near-stoichiometric lithium niobate, the dark storage time and gating efficiency can be increased compared with previous work. The underlying physical mechanisms of gated recording and the effectiveness of the gating process responsible for this manifold improved performance are discussed, and bipolarons and small polarons are identified as the responsible photorefractive species.

Light-induced absorption of cerium-doped lead barium niobate crystals

Tetragonal lead barium niobate (Pb(1-x)Ba(x)Nb(2)O(6);1-x<0.63) crystals are promising photorefractive materials for applications such as holographic data storage. Measurements of light-induced absorption in Ce-doped lead barium niobate (Pb(0.5)Ba(0.5) Nb(2)O(6)) were performed. The induced absorption that was due to the presence of shallow traps was as large as 0.3cm(-1) at 633 nm and exhibited saturation behavior at green-pump intensity greater than 2W/cm(2) . The temporal profile of the dark decay was a double exponential, and the activation energies of the slow- and the fast-decaying components were determined to be 0.16 and 0.3 eV, respectively.

[A research for basic properties of distortion product otoacoustic emissions in normally hearing subjects]

With ILO-92 Otodynamics Analyzer, distortion product otoacoustic emissions (DPOAEs) at the 2 f1-f2 frequency were recorded from 86 normally hearing ears in response to four groups of different primary levels (L1 = L2 = 75 dB SPL; L1 = L2 = 65 dB SPL; L1 = L2 = 60 dB SPL; L1 = 65 dB SPL, L2 = 50 dB SPL). The average DPOAEs-gram demonstrated a bilobed contour with two peaks at approximately 1.5 kHz and 5 kHz and "notch" between 2.5 kHz and 3 kHz. Moreover, the contour of DPOAEs-gram had no obvious changes with sex, ear or primary stimulus levels differences. While the primary levels increased, the amplitude of DPOAEs gradually increased, which was about 55-65 dB SPL below the primary levels. At each frequency from 1-6 kHz, statistical analysis showed that there existed significantly different DPOAEs level under four groups of different primary stimulus levels.

Shear stress and the endothelium

Shear stress and the endothelium. Vascular endothelial cells (ECs) in vivo are influenced by two distinct hemodynamic forces: cyclical strain due to vessel wall distention by transmural pressure, and shear stress, the frictional force generated by blood flow. Shear stress acts at the apical cell surface to deform cells in the direction of blood flow; wall distention tends to deform cells in all directions. The shear stress response differs, at least partly, from the cyclical strain response, suggesting that cytoskeletal strain alone cannot explain it. Acute shear stress in vitro elicits rapid cytoskeletal remodeling and activates signaling cascades in ECs, with the consequent acute release of nitric oxide and prostacyclin; activation of transcription factors nuclear factor (NF)kappaB, c-fos, c-jun and SP-1; and transcriptional activation of genes, including ICAM-1, MCP-1, tissue factor, platelet-derived growth factor-B (PDGF-B), transforming growth factor (TGF)-beta1, cyclooxygenase-II, and endothelial nitric oxide synthase (eNOS). This response thus shares similarities with EC responses to inflammatory cytokines. In contrast, ECs adapt to chronic shear stress by structural remodeling and flattening to minimize shear stress. Such cells become very adherent to their substratum and show evidence of differentiation. Increased adhesion following chronic shear stress has been exploited to generate vascular grafts with confluent EC monolayers, retained after implantation in vivo, thus overcoming a major obstacle to endothelialization of vascular prostheses.